Sigil of Myrkul is a uncommon Enchantment card from Commander Legends: Battle for Baldur's Gate (CLB), collector number 147. Current market price: $0.28 (foil $0.30), TCGplayer market prices via Scryfall.
At the beginning of combat on your turn, mill a card. When you do, if there are four or more creature cards in your graveyard, put a +1/+1 counter on target creature you control and it gains deathtouch until end of turn. (To mill a card, put the top card of your library into your graveyard.)
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