Hearthstone's upcoming expansion Kobolds and Catacombs lands on December 7, and is loaded with treasure, traps, and dungeon crawling madness. Today, we're unveiling a wild Mage spell that should be a lot of fun to play – and a lot of fun to watch in action! Check out Deck of Wonders!

Deck of Wonders places 5 Scroll cards into your deck, which autocast a random spell for free when drawn – you can't pick the targets, and the spells can be from any class, much like a Yogg-Saron trigger. They read "Cast a random spell. Draw a card. Cast this when drawn." Spells can be from any class and are not limited to Mage spells!

Casting a spell for 5 that doesn't do anything immediately might seem like a tough sell, but you can take that price and tap into cards like Arcane Tyrant so that you won't have a "blank" turn when you set up your Deck of Wonders.

Extremely relevant to this conversation, Scrolls also have a casting cost of 5 (they will play for free when drawn, don't forget), meaning they can be combined easily with other cards that take advantage of higher-casting cost cards in your deck, like the recently revealed Spiteful Summoner. These random spells do not count toward things like Open The Waygate or spell trigger cards like Violet Teacher. If you want to get really tricky, you can use something like Hemet, Jungle Hunter to trim your deck down to size so that every draw has a great chance to hit one of your free spells.

However, if you manage to Thoughtsteal a Scroll, or acquire one through other means – they can still be hard cast for 5 to fire off a random spell and draw a card.

Hearthstone principal game designer Mike Donais walks us through the creation of Deck of Wonders and ways to squeeze some extra value out of embracing the "invest now for a lot of potential value later" package.

"I think a lot of streamers will include the card in their deck because it's a fun card," says Donais. "But I think they're going to have to get some good synergies like Arcane Tyrant, Spiteful Summoner, and those other spells that haven't been revealed yet to actually make it worth running in a competitive way."

Deck of Wonders changed a bit during development as well, most notably moving from an "all at once" blast to a more nuanced effect that you can build around.

"We liked the idea of a deck of many things or something like that - it created fun situations," says Donais. "At one point, the card cast the random spells all right away, kind of like Yogg-Saron, but it was a little too close to Yogg-Saron, and getting that impact immediately was really high variance as opposed to one spell, one spell, one spell. It also lessened the chance of just clearing the board. We had it costing different amounts, we ended up with 5 being the right number because it has some synergy with other cards like Arcane Tyrant, and the spells it shuffles into your deck also have a cost of 5, so they work well with Spiteful Summoner. The actual text box changed a little too, we wanted it to work if it was Thoughtstolen. So that if you don't draw it, you can play it for 5 and get it out of your hand and maybe do something cool."

Deck of Wonders looks like it's going to take some serious combinations to take seriously, but it should be epic to watch carefully curated spell chains fire off as a well-tuned deck takes advantage of all the random blasts, bolts, and more that pop out of the tumultuous tome. And of course, there will always be that one time that things go completely wrong (or right!) when two back-to-back Pyroblasts just happen to flip up for a scorching finale!

Check out more Kobolds and Catacombs cards as they are revealed on the official Blizzard site!