User blog comment:Masterzach32/Yomu - the Dark Wind/@comment-7709681-20140131010404/@comment-7481207-20140131100955

The maximum death chance with rank 3 ultimate would be around 98%, as 1000 AP is far from the maximum AP you can get.

Still, an ability as random as that ultimate with so much at stake is toxic. It could potentially kill a full health tank with only 100 AP. The chance is only 4% sure, but it still exists. And the same is true for high percentages, even with really high death chances, unless it reaches 100% (which would require 1250 AP), it can fail, putting your ultimate on a high cooldown and losing all your wind without accomplishing anything.