Kronii, Keeper of Time

This spell cannot be countered.
Indestructible, Flash
You may cast spells as though they had flash.
Your opponents may cast spells and activate abilities only when they could cast a sorcery.
Whenever a creature you control dies, you may
exile it with 2 time counters on it. It gains "At
the beginning of your upkeep, remove a time
counter from this card. When the number of
time counters on it reaches 0, return this
card to the battlefield."