Grumbo, Party Scrungler

Haste, Shroud
{t}: Target player gains control of Grumbo.
{1}: Put a party counter on Grumbo. It deals 1
damage to its controller. Any player may activate
this ability or pay {1} to counter it.
When Grumbo leaves the battlefield, it deals
damage to each player equal to the number of
party counters it had on it.