Overview:

At some point sooner or later, the average player will have to make the decision of whether to buy Randuin's Omen or Frozen Heart. Why would anyone need to buy either of these items? Well, the answer is not as simple as one might think, even though the basic ideas may be similar. In fact, both of these two items have been embraced by a majority of the player base in the sense that Randuin's Omen is perhaps a very common buy for the typical top laner in the current meta, but how many players really sit down and think about the pros and cons of two items that can get the job done in similarly different ways?

Randuin's Omen:

With a 19.53% buy rate in all North American solo queue games (source: lolking.net), Randuin's Omen has become one of the go-to items for many top lane bruisers and junglers. Having been bought in nearly 1/5 of all games played, what makes the item so popular when compared to Frozen Heart which can do a similar job? When completed, Randuin's Omen will grant a champion 500 health and 70 armor along with a unique active and passive. The passive reduces the attack and movement speed of any champion that uses a basic attack on the player carrying the item while the active applies a slow to all nearby enemy champions for a few seconds. What particularly stands out about this item is the ability to slow nearby enemies along with the massive health boost. In addition, the slow for any champion who attacks the wielder is extremely useful in a 1v1 trade which most frequently occurs in the top lane.

Pros:

- Better for 1 vs. 1 duels and trades

- Active slow to help chase/escape

- Bonus health along with armor for lane sustainabilty

Cons:

- Harder to apply passive in teamfights if enemies do not auto-attack you or ignore you

- In order to apply active slow, one must dive into enemy team

Frozen Heart:

Unlike Randuin's Omen, Frozen Heart is only picked in about 4.63% of all North American solo queue games (source: lolking.net). The reason why it may be less widely popular is due to the fact that is offers considerably less defensive stats than one may think. Sure, you get 25 more armor out of buying Frozen Heart, but it offers 400 mana in place of 500 health you would otherwise need for trades and sustainability.

However, when it comes to teamfights, Frozen Heart applies a 20% attack speed reduction to all enemies nearby which basically takes away 1/5 of all auto-attack based damage. This attack speed reduction can be extremely useful against particular team compositions that are heavily reliant on auto-attacks for damage. In comparison to Omen, Frozen Heart is more of a late-game item for certain situations whereas Omen is more mid-game based item for general use.

Pros:

- AOE attack speed slow more optimal in teamfights against auto-attack damage based team comps

- 400 mana and 20% cooldown reduction for champions that have emphasis on their spells and are mana heavy (i.e. Ryze)

- Slightly more armor than Omen (25)

Cons:

- Very situational item against enemy teams with lots of auto-attack damage

- No extra health means lower sustainability in teamfights

- Build path is slightly more awkward than Omen's

Conclusion:

Randuin's Omen and Frozen Heart are both perfectly viable items that are good at doing the job they were specifically assigned to. However, both items are very different in terms of which situation you should buy them. Randuin's Omen is more of a 'default' item that most junglers and top laners buy for 1v1 trades and lane sustainability whereas Frozen Heart is more oriented towards teamfighting and reducing the damage output of multiple champions in the vicinity.

The only time one should buy Frozen Heart is when the enemy team has champions that rely on auto-attacks and attack speed as their main source of damage. In team compositions with less of this threat, a Randuin's Omen will suffice for its AOE slow and passive slow applied to enemies who attack that particular champion.