Currently the tooltip states "If the target has a higher health % than Irelia, she Stun icon stuns the target for the same duration instead.", but Irelia can stun the enemy when both champions are at 100% health.
better nerf her
she does not, BUT is shes even 1 hp missing from full she will
Probably Irelia's base Hp is lower than targetted champion.
It's intentional. I know it's confusing, but it's not a bug. Riot even confirmed it before I believe.
It's more than likely coded to be less than or equal to for the stun and greater than for the slow. They probably just wanted to make sure she did something in the unlikely scenario that both are 100% and went with the stun.
