Does item effects stack with other item effects?

Question

For an example if 2 people had frozen heart would it stack? will of the ancients stack so does other items stack as well?

I meant 2 people as in both of them having it, would they stack with one other since they're different people?

Answer 1

Auras are unique effects that are only applied one time.

But there is an exception when it comes to buffs:

An exception to this rule is in the event that multiple champions are carrying an item with the same beneficial aura effect, each of those two champions will receive two instances of the aura buff: one from the item they are carrying, and a second from the aura of their ally. If a champions is near both of the champions with the same aura item, it will only receive one instance of the aura. No champion can ever receive more than two instances of a unique benevolent aura, regardless of how many nearby allies are providing the buff.

source

Answer 2

If it says Unique on it, then no they will not stack if you buy two or more of those items.

Frozen Heart for example says UNIQUE Passive: Nearby enemies suffer −20% attack speed.

If your whole team gets a frozen heart, the enemy team is not slowed -100% attack speed.

Answer 3

Will of the anciencts only stack because you can have the aura yourself and get one from another team member, since its the enemy you affect with frozen heart it wont stack since they cant be affected by 2 similar enemy debuffs that is unique.

Answer 4

Only the two ppl with the same buff aura will have double buff. Such as WoTA you get your teammates aura, and keep your WoTA's buff. But everyone else without the item will only have one aura.