Master Yi, Unstoppable

[Level 3][>] I cost {2}{CR} less. (While you have 3+ XP, get the effect.)

[Level 6][>] I cost {4}{CR}{CR} less instead.

[Level 11][>] I cost {6}{CR}{CR}{CR} less instead.

[Level 16][>] I can't be chosen by enemy spells and abilities.