Yasuo True Powerspike
As a OTP yasuo main, I feel that Infinity Edge isn't his most powerful power spike. This is because IMO, yasuo is still extremely squishy (unless you bought PD) and his real power spike is when he buys BT. In all my games, I start really popping off when I finish my BT because of the extra sustain to help in team fights and just plain survivability.