Niveus, the blue lich

Deathtouch, Hexproof
{t}, Pay {x} life: Tap creatures target opponent controls, where X is equal to target opponents creatures. Creatures don't untap during target controller's next untap step unless they pay {2} life per creature.
{t}, Pay {x} life: Summon a 2/2 Helwalker token equal to X spent, where X is equal to your tapped mana.