The Lich, Lord of Bones

The Lich, Lord of Bones' power and toughness is equal to the number of Skeletons on the battlefield

Whenever a Skeleton is regenerated or returned from the graveyard to the battlefield, create two 1/1 black skeleton creature tokens.

{5}{b}{b}{b}{b}{b}: Return all Skeletons from all graveyards to the battlefield under your control