The Midgard Serpent

On each upkeep, put a +1/+1 counter on The Midgard Serpent.
Remove 10 +1/+1 counters from the Midgard serpent, then
search your deck for a card named: Ragnarök, worlds end.
Whenever a creature deals combat damage to The Midgard Serpent
put 9 Pace counters on that creature. On each upkeep, remove
1 Pace counter from that creature. When there a 0 Pace counters
on that creature, its owner sacrifices that creature.