The point is once yi hits you once, you're as good as dead if you can't 1v1 him. Yi will basically get... 6 procs of botrk in 3 autos or something like that. Which also means his q will get reduced by 6 seconds of cd. So you literally have to turn and fight if he gives you a single tap.
Devourer is just that enchantment that's either hella broken, or hella weak. I really wish it would stay the latter, cause I'm sick of dealing with yi, ww, and udyr. And skarner. And xin. And kayle. And shyv. Because all of these fuckers don't need more love in the jungle, yet they are pretty much exclusively the only champs that benefit from the devourer buff. And it's more than 6 of them, so I can't ban out all of them, even with the enemy's help.
Oh, and aatrox.