Ancient Cellarspawn

Mana cost: {1}{B}{B}
Type: Enchantment Creature — Horror
Power / toughness: 3 / 3
Set: Duskmourn: House of Horror Commander #47 (rare)
Price: $7.05 USD

Each spell you cast that's a Demon, Horror, or Nightmare costs {1} less to cast.
Whenever you cast a spell, if the amount of mana spent to cast it was less than its mana value, target opponent loses life equal to the difference.

Ancient Cellarspawn has 2 printings, first in Duskmourn: House of Horror Commander (2024). EDHREC ranks it #2,542 among Commander cards. It appears most in Captain N'ghathrod decks (9,063 on EDHREC). 1 public deck on TCG runs it. It has 4 official rulings.

Legality

commander: legal
legacy: legal
vintage: legal
pauper: not legal
modern: not legal
pioneer: not legal
standard: not legal
brawl: not legal

Public decks that run Ancient Cellarspawn

Miracle Worker - Duskmourn: House of Horror Commander, led by Aminatou, Veil Piercer

Commanders that run Ancient Cellarspawn most

Deck counts from EDHREC.

Often played with Ancient Cellarspawn

Cards that show up in the same decks on EDHREC.

Rulings

2024-09-20: If the spell is no longer on the stack when Ancient Cellarspawn's last ability resolves, use its mana value as it last existed on the stack.
2024-09-20: Ancient Cellarspawn's last ability resolves before the spell that caused it to trigger. It resolves even if that spell is countered.
2024-09-20: To determine the total cost of a spell, start with the mana cost or alternative cost you're paying, add any cost increases, then apply any cost reductions. The mana value of the spell remains unchanged, no matter what the total cost to cast it was.
2024-09-20: For spells with {X} in their mana costs, use the value chosen for X to determine the spell's mana value.