Death Warden

Whenever another creature card would be sent to the graveyard, exile it instead.
Whenever Death Warden exiles a card, put a +1/+1 counter onto Death Warden.
When Death Warden dies, return all cards exiled by Death Warden to their owner's graveyards. Create X 1/1 Colorless Spirit creature tokens and X 2/2 Black Zombie creature tokens. X is equal to the number of +1/+1 counters on Death Warden.