SCP-096

This creature enters the battlefield under no
player's control (This creature has no controller).
Indestructible, trample
Whenever a creature attacks, flip a coin. If it's
heads, put a seen counter on that creature.
At the beginning of each upkeep, untap this creature, then it attacks a creature that player
controls with a seen counter on it at random (Blockers may be declared).
Whenever a creature blocks SCP-096, it gains a
seen counter.