Grimgrin, Corpse-Born (Oversized) [Commander's Arsenal Oversized] Human Assassin if Tombstone Stairwell is on

if Tombstone Stairwell is on the battlefield

or becomes tapped

{T}: Gain control of target creature with power less than or equal to Old Man of the Sea's power for as long as Old Man of the Sea remains tapped and that creature's power remains less than or equal to Old Man of the Sea's power

Round each loss up

every leaf

Grimgrin, Corpse-Born (Oversized) [Commander's Arsenal Oversized] Human Assassin if Tombstone Stairwell is onSet: Commander's Arsenal Oversized Type: Legendary Creature Zombie Warrior Rarity: Mythic Cost: {3}{U}{B} Grimgrin, Corpse Born enters the battlefield tapped and doesn't untap during your untap step. Sacrifice another creature: Untap Grimgrin and put a +1 +1 counter on it. Whenever Grimgrin attacks, destroy target creature defending player controls, then put a +1 +1 counter on Grimgrin.