Kywin, Shadow of the Night

Kywin, Shadow of the Night is unblockable.
As long as you control 3 or more assassins,
assassins you control get +1/+1.
Whenever Kywin, Shadow of the Night deals
damage to an opponent, give them a hit counter.
At the beginning of your upkeep, create {x} 1/1 unblockable assassin creature tokens, where {x} is the number of hit counters target
opponent has -1.