Nuclear Submarine

Crew 4, Shroud, Skulk, Radioactive (Whenever
this creature deals damage to a creature, that
creature gets a radioactive counter. Creatures
with radioactive counters take 1 damage at the beginning of each upkeep and have this ability. If
this creature deals damage to a player, that player
gets a Nuclear Fallout Enchantment Token with
"At the beginning of your upkeep, you lose
10 life minus the amount of times this ability
has been activated.")