Treasure Goblin

Treasure Goblin is indestructible, cannot attack and must block each turn if able.
When Treasure Goblin enters the battlefield, target opponent gains control of it. Put X Treasure counters on it. Shuffle it into its owners library when there are 0 Treasure counters on it. Whenever Treasure Goblin is dealt damage, the controller of the source draws a card. Remove a Treasure counter from Treasure Goblin each time this effect happens.