Pact of Bloodshed

At the beginning of your upkeep, put a counter
on Pact of Bloodshed. Creatures you control have Lifelink and +X/+X, where X is the number of counters on Pact of Bloodshed.
When five counters are on Pact of Bloodshed,
destroy all creatures on the battlefield. You take
damage equal to the number of creatures
destroyed this way. Then, exile Pact of Bloodshed.
"You wish to see your oppressors destroyed. I shall
grant you that wish."