Hearthstone is as alive as a game can be, but it’s about to get a heaping dose of death. The digital card game’s next expansion, Knights of the Frozen Throne, comes out in August for PC and mobile. It’ll add 135 new cards, including some that will turn Hearthstone’s classes into Death Knights, which will give them new powers.

Expansions are Blizzard‘s most important tool for keeping Hearthstone popular. Each time it releases a new set of cards, it gives fans a reason to spend more money in the game (mostly on packs so that they can acquire all of those new cards). But expansions also keep the game fresh. New cards means new strategies and new decks, changing the way everyone plays Hearthstone and starting a new era of deck discovery. For many, Hearthstone is at its most fun right after a new expansion launches.

We had a chance to talk with Hearthstone’s principal game designer Mike Donais about the challenges of continuing to keep Hearthstone fresh with these big expansions. We explored the process behind creating these new Death Knight heroes, fan reactions to the last couple of sets, and more.

Image Credit: GamesBeat

GamesBeat: It seems like reception to Un’Goro was very positive. Fans didn’t have a lot to complain about. What do you think made it work so well?

Mike Donais: I think it was a lot of different things. It had a really cool vibe to it. People love the fantasy of dinosaurs. The Elementals were a good combination with that. People recognized it. It was bright and fun and happy. All that combined together to make a nice theme, and then mechanically, one thing we did very heavily in Un’Goro was put in a lot of different build-arounds. Not just a theme for every class, but two themes in every class.

People could spend a lot of time exploring those different themes. Sometimes only one of the themes played out. Sometimes two played out. That’s why you’re seeing more than nine different decks getting played. There are two decks in some classes, or even three. You see Dragon Priest, Spell Priest, Silence Priest. Same is true for Rogue. We saw Miracle Rogue, Quest Rogue, and now in the last week or so we’ve seen Jade Rogue. All those different options are really good.

Another thing we did was make a lot of the power level numbers right around the level where you want to experiment with that card. We call it 7/10 power level. That means, in the right situation, depending on what else is out there, that card is interesting to think about or experiment with. It meant, for a lot of people, playing a lot of different decks.

GamesBeat: Were any cards more popular than you anticipated? Stonehill Defender, maybe?

Donais: Stonehill Defender’s a good one. We thought it would be good in Paladin because of the obvious Tirion. We weren’t sure how good it would be in other classes, but as time goes by it’s going to get played in more classes, because it has some really cool options.

GamesBeat: On the flip side, Mean Streets of Gadgetzan didn’t have quite as warm a reception from fans. What about that expansion do you think didn’t work as well?

Donais: Hmm. Well, I think the reception for Mean Streets was pretty positive initially. I think people maybe got tired of it quicker. They figured out what to do with it and weren’t happy with exactly what to do with it. But in general, Mean Streets of Gadgetzan was more positive than negative. I think people just explored all the possibilities quicker and it got a bit stale. People figured it out and then just played the same decks. Having the rotation with Un’Goro and then having a lot more viable decks for each class really helped.

Image Credit: GamesBeat

GamesBeat: With Knights of the Lich King, you can play a card and then turn your hero into a Death Knight. Does this kill the possibility of whole new classes ever coming to the game?

Donais: We’ve always said that we like the nine classes we have. We work really hard to try to give some class identity to those nine classes, and it’s tough, because nine is a lot. Adding a tenth or eleventh class isn’t something we’re interested in. It’s too hard to make class identity exist when there are that many different classes. So yeah, we’re not excited about the idea of making new classes.

GamesBeat: How long has the team been thinking about a Lich King expansion?

Donais: A Lich King expansion is something we’ve kicked around since even before launch. Everybody loves the Lich King and Icecrown and that fantasy. Warcraft III had an awesome campaign there with a great story. Ever since then, it’s been a great idea to do it eventually. But I think doing some — showing what Hearthstone is about, showing that it’s more fun and relaxed and funny and warm and inviting was important. We’ve established that over the years. Now we can break away from that and do something where everyone dies instead. People realize that’s not Hearthstone’s identity, that it’s an exception to the rule. That really helps us.

GamesBeat: Everybody’s dying, which sounds dark, but it could also be kind of funny in a way. Should we really expect something that’s completely dark and serious in tone?

Donais: It’ll still be Hearthstone-ified. We’ll be true to the Death Knight fantasy, making these pretty dark heroes. I don’t know if you’ve seen Anduin’s art, but he’s scary. He’s this weird shadow guy. I love his art. I think that delivers on the sort of dark fantasy of the Lich King. But there’s also going to be some cool, fun stuff. The missions especially have a cool storyline with some fun lines as you go through. As always, our flavor text is sort of relaxed and funny. I like the mix that we do. I think it’s going to go over well.

Image Credit: Blizzard

GamesBeat: The cards that turn heroes into Death Knights are legendary rarity. Is it going to be like Quest cards, where each class gets two legendary cards this expansion?

Donais: Yeah, exactly. Each class will get two legendaries, a minion, and then a hero card.

GamesBeat: With this big undead theme, was there any thought of making undead a tribe, like Elementals in the last expansion?

Donais: Yeah, we talked about that a lot. Even for Naxx we talked about doing undead as a new minion type. We decided that it’s not quite worth it. Maybe one day we’ll do that, but we don’t have any plans for it right now. It’s certainly the minion type that has come up the most often. Elementals was the other one that came up a lot. We obviously did that. We did Mechs already. So I can totally see that at some point.

GamesBeat: What are the drawbacks to making it a tribe?

Donais: I don’t think there are too many disadvantages. One of the reasons we didn’t do it is because we had just done Elementals in Un’Goro. Doing two new minion types in a row didn’t really make sense to me.

GamesBeat: What was the goal in designing new hero powers? You talked about class identity. I’m sure designing nine hero powers the first time around was already a pain. Now you have to give each class a new higher-tier one.

Donais: Yeah, it was definitely difficult. That’s what we spent the most time on. We did a lot of iteration. Rexxar changed maybe 10 different times. He did totally different things throughout. Early on, we had him summoning 5/5 zombies for each beast that died this turn. Then we changed that to be summoning all the beasts that died this game, something like a N’Zoth effect for beasts. Then we changed him again to summon three beasts from your deck. We liked those two designs because they’re kind of build-around. You want to play big beasts, but not small beasts, which is different from a lot of hunter decks.

Image Credit: Blizzard Entertainment

GamesBeat: With the Hunter hero power, the new build-a-beast thing, it’s a kind of late game tool. In Un’Goro, Hunters got Swamp King Dred, which is another control tool, even though Hunter is typically a faster-paced deck. Why focus on giving Hunter these kinds of powers?

Donais: One thing we’ve had a lot of success with is giving people different deck types to explore. Even if people don’t end up succeeding at creating a tier one hunter control deck with this card, it’ll be fun to try it out, see how slow or controlling a hunter deck they can build. Should they put neutral life gain or neutral taunts in, or should they just use a more aggressive board control deck? The Battlecry on Rexxar is pretty good for that. It does two damage to all enemy minions and gives you five armor. That’s fairly defensive, fairly controlling. It might give you enough time to start using the late-game stuff. But I suspect that your mana curve is going to be pretty low in that deck. Once you’re building beasts, you can easily spend all your mana on that every turn. You don’t need to worry about having expensive spells in your deck.

GamesBeat: The other new thing in the expansion is Lifesteal. What are you hoping to accomplish with that new ability? Did you want to slow down the game some more?

Donais: Lifesteal is a smaller mechanic in the set. It’s a bit like Poisonous, where there’s only a smaller number of cards. But it’s something that is pretty intuitive and fun. People like the idea of Lifesteal. It’s existed in many games, and on all those games people love gearing up with items for it, stuff like that. We’ve always liked the fantasy of it. We’ve explored it a bit in the past and it’s worked out really well. We had a Warlock card and a Pally card that had Lifestealing. So we thought about what classes are really good at gaining life, what classes it would fit with flavor-wise. Paladin and Priest came to mind.

Priest has this shadow form, darkness, life-stealing thing going on in WoW. It made sense to put it there. We’re exploring it a bit. There will be cards specifically in the classes, and then a couple of neutrals. We’re always really careful with life gain in neutral, because really life gain in neutral means life gain in Warlock. That has to be balanced a bit differently because of their hero power.

GamesBeat: Are we going to see some older cards change to use the keyword, like Wickerflame Burnbristle?

Donais: Yeah, we changed the text of two minions — Wickerflame Burnbristle is one of them — to say Lifesteal instead of their old text.

Image Credit: Blizzard Entertainment

GamesBeat: You brought up Warlock. As happy as everyone was with Un’Goro, that was maybe the weakest class in the expansion. Is Warlock getting some help?

Donais: They have some cool stuff. I don’t know if one expansion is going to make them go from pretty weak to pretty strong. We’re always careful with Warlock, because Warlock has been really strong since launch, except for in this one expansion. It might have to creep up slowly over multiple sets. We put some good cards in there and we’ll see what happens. I’m sure that as time goes by, it’ll get better and better.

GamesBeat: I personally didn’t mind seeing Warlock sit an expansion out.

Donais: That’s the thing. Once it’s been a strong class for three years, it’s not that big of a deal if it’s a bit weaker for one expansion and then grows over time again.

GamesBeat: Are we going to be seeing more Discover cards? It seems like every expansion has a thing it introduces, like tri-class cards, and then it disappears after that set. But you introduced Discover in League of Explorers and it has been a part of every expansion since then.

Donais: Discover’s a really fun mechanic. It’s a way to do the Webspinner fantasy — add a random beast to your hand — without bleeding into other classes. One of the things that happened with Webspinner is sometimes you would get a beast from Druid, and it would feel kind of weird. When we made Discover, we made it specifically hit your class and neutral only, which was an improvement. You get less strange cards, off-class cards getting played. In addition to that, it reduced the variance, rather than getting a totally random thing. Sometimes it was a Wisp, or something. You would get to choose the best one. That made the game a bit more consistent.

It gave you an interesting decision — what card do you want from Discover? — and then it gave you another interesting decision around how you wanted to play that card. It only went into your hand. It didn’t go straight into play. So there’s a lot of decisions around Discover. It let people who were very good win even more, and I think people appreciate that. It also has some variance, though, because sometimes you’re playing against somebody and they Discover a card you’re not expecting, or they Discover the perfect card for a situation, and that gets you upset or excited.

Image Credit: Jason Wilson/GamesBeat

GamesBeat: So expect more Discover cards in Frozen Throne?

Donais: Yeah, I think Discover, or at least some kind of randomness, will always be around. It’s fun. A lot of people really love it. It makes playing 50 games in a day a lot more interesting, because it’ll be a little bit different every game. But like every mechanic it’ll ebb and flow. Sometimes there will be a bit more and sometimes a bit less.

GamesBeat: Is it likely we’ll see new versions of cards we’ve already seen in the past, like Ragnaros? Some characters that we’ve already seen are important to the Lich King story. Or is one Tirion already enough?

Donais: We did do characters from the past recurring. The way we did that this time is the nine heroes. Because we’re doing these nine big splashy heroes, like Jaina and Rexxar, we didn’t want to do a lot of other stuff that you’d already seen. Mainly that’s what we’re focusing on, the returning heroes. Seeing Jaina in her Frost Lich form, or Rexxar as this guy who’s stitching together even scarier beasts is a pretty cool story.

GamesBeat: You haven’t announced an Arthas card yet, but assuming one’s coming, there must be a lot of pressure to making that specific card. What’s the challenge of making a card for a character like that, an iconic Warcraft hero or villain like Medivh? Is that a different feeling from making just another legendary?

Donais: Yeah, when we’re making a card like Medivh there’s a lot that goes into creating that fantasy. We want something that’ll make you go, “Wow.” We want people to feel like we deliver on, “Oh, yeah, that makes sense for Medivh.” Both the story and the mechanics. It’s really tough to do. It was the same with Rexxar. Hey, we know what Rexxar did before, but what is he going to do now? For each of the hero cards it was like that. It was very tough to design. We do a lot of iteration and discussion. We probably pitched 50 to 100 ideas for each card, like Medivh or the hero cards, and went through a lot of iteration and playtesting on each of them.

Image Credit: GamesBeat

GamesBeat: Is there ever a pitch for one of those cards that you don’t think is right for the character, but ends up on a different card?

Donais: Oh, yeah, all the time. Build-a-beast used to be a spell in this set. You just played the spell and you got to Discover two beasts and stitch them together. We liked the spell so much that we promoted it up to the hero card for Rexxar. Stuff like that goes back and forth all the time.

GamesBeat: You somewhat famously, before the last expansion came out, apologized in advance for the Priest legendary card. You said it was going to be powerful. You got a little mockery when Lyra first turned up, and then you had the last laugh when it actually turned out to be very powerful. Are there any other legendary cards we need to look out for this time?

Donais: My main thought on that is, just don’t be like, “Oh, this card is trash,” or “This card is busted” before the set comes out. The chance of being right is not that high. The chance of being wrong is pretty decent. Think about it, think about how you’re going to play it, talk about it. It’s fun to talk about this stuff. I’m not saying don’t talk about it. But don’t write everything off or get too upset about something until you’ve seen it played with everything. It’s fun to theorize. I love theorizing about stuff like that. But it’s also fun to explore once the cards come out. Have fun playing them and don’t disenchant your cards as soon as you open them, because they might be good.

GamesBeat: Constructed is the main format you’re thinking about in the design of these cards, but how much do you consider Arena when you’re making expansions these days?

Donais: We actually talk and work on Arena stuff, but we try not to use specifically Arena and card design together. We have different tools. We have this tool that lets us adjust drop rates in Arena. We’re slowly making changes to that to make Arena more fun and balanced. We don’t think that any one patch is going to get us there, but we like the iteration process. Over time we’ll get closer and closer, so bear with us as we adjust toward that. We have some small changes in the last two patches, and then we have some more changes in the release of the new expansion that I’m excited about trying and seeing how people react to them.

GamesBeat: Going back to the last expansion for just a second, the Quest mechanic was a big focus for Un’Goro. Were you happy with how that went? Not all the quests saw a lot of play, but they encouraged a lot of deck-building.

Donais: Yeah, it had the perfect first couple of weeks where everyone was experimenting with online quests, trying to find the best version. That’s awesome. It’s what new expansions are all about. After things got figured out, there were still a bunch of quests that needed to be better, or could be better. The nice thing about that is, there are five expansions still available in Standard, plus Wild, and people are having success with different quests, like Priest in Wild for example.

I’m excited to see how the next five expansions modify those old quests. People can go back to them and try them out – try the Warlock quest or the Paladin quest with new cards. That’s something we love to do and love to see. We’d do one pirate per set, or one murloc per set, and every time a new pirate or murloc came out, people would go back to the old pirate or murloc decks and try those out, until suddenly maybe pirates and murlocs are a big deal. Similar things can happen with the quests, where we release one new card that modifies them and people can go back and try them out with every expansion.

Image Credit: Blizzard Entertainment

GamesBeat: It’s funny, because the Priest quest right now isn’t a very popular one, but I had a lot of fun playing with it. With Deathrattles being a big thing in the next expansion, it seems like that’s a Quest card that could become more powerful in this set than it was in the last.

Donais: Yeah, I think there’s a couple of new Deathrattle minions in the Frozen Throne expansion, so people will go back and experiment with that again. It’s already very close to being a good card. It’s like starting with an 8/8 taunt full heal card in your hand, but you’re not allowed to play it until turn 6-10 or something like that. Because of that, you’re like, “I don’t want this in my opening hand.” It’s very cool. I had a lot of fun with it in Wild. I think over time people will experiment with it and find a place for it in Standard too.

GamesBeat: Is it challenging managing so many different minion tribes with each new expansion? You have Pirates, Elementals, Dragons, and more. Do you feel like you have to check those boxes every time, or is it okay for an expansion to not have a lot of certain tribes?

Donais: We leave tribes out sometimes and that’s cool. It’s a lot easier to make expansions when we have tools like that, actually. I love making cards that are narrow or build-around or situational, because then, if they’re good, they’re not good in every deck. They’re only good in some decks. Being able to put an Elemental in Priest and a Dragon in Priest makes it easier to design 10 priest cards, because there’s two right there. You only have to come up with eight more.

GamesBeat: Speaking of dragons, it was kind of a surprise — a lot of people thought dragon decks would be dead coming out of the rotation. There was really only one dragon in the last set, but it was such a good one that Dragon Priest still became a thing. We saw Curator become a real popular card all of a sudden. Did you think that dragons would still have such an impact after rotation?

Donais: We playtested the dragon deck, partly because it’s a fun deck to build and play, and partly just to see how good it was. We had an idea that was still going to be pretty good. We wanted to make a nice defensive cards for dragon decks and control decks in general. We saw that with the one dragon we did ship in Un’Goro. Having a nice taunt, having a nice area-of-effect landing on two means that if you do live to turn eight, you’re going to have a good control card there.

GamesBeat: Do you think Hearthstone works better as a slower game, or as a faster one?

Donais: My hope is to have a variety of decks out there – some fast decks, some slow decks, some combo decks, some tricky decks. I like the variety. Different types of players can play different types of decks. Everyone likes different types of decks, and people like switching between their decks sometimes.