Talk:Master Yi/@comment-2042085-20130724122228/@comment-3974211-20130724123544

The critical strikes on Alpha Strike and Double Strike have a damage modifier of 60%/50% (respectively). This means that critical damage from all sources is reduced as well. The bonus 50% you get from Infinity Edge is reduced to 30 / 25% respectively.

Jayce's Hypercharge applies a damage modifier too, 80 / 90 / 100 / 110 / 120%. At max rank with Infinity Edge, Jayce's Critical Strikes do 180% critical strike damage (so 300% damage in total).

It does stack additively, there is just a modifier.