Unwilling Vessel

The counter engine here isn't the payoff; it's the ammunition for a death trigger that only pays out when the creature is gone. That inversion is the whole design tension. Eerie stacks possession counters passively, off enchantments entering and Rooms fully unlocking, but a 3/2 with vigilance sitting on four or five counters does nothing with them while alive. The value is deferred entirely to death: whatever count it has accrued becomes a flying Spirit of that size, meaning the incentive runs backward from most counter creatures. You are not protecting this body so it grows into a threat; you are feeding it counters and then wanting it to trade, block into removal, or get chumped through. It turns a combat loss or a targeted kill spell into an upgrade, converting a grounded Human Wizard into an evasive token that often outclasses what killed it. The vigilance is quietly load-bearing, letting it attack for pressure without surrendering the block that might trigger the payoff on your terms. It rewards an enchantment-dense shell not for the usual reason (a wide board of permanents) but because each trigger raises the ceiling on what the creature is worth dead, which is a strange and specific thing to build a blue three-drop around.