Power Word Kill

Treat the target's current hit point total as though it were lowered by 5 times your tier. For example, a 3rd-tier archmage casting mythic power word kill would instantly kill a creature with 85 hit points or fewer.

You can target a creature with more hit points than this spell could normally affect, causing it to become exhausted.

Augmented (6th): If you expend four uses of mythic power, the magic of the word lingers around the target. Until the beginning of your next turn, if the target's hit point total drops to the point that this spell would have killed it upon casting, it's instantly slain.