Hollowmurk Siege is a rare Enchantment card from Tarkir: Dragonstorm Promos (PTDM), collector number 192p. Current market price: $0.99 (foil $0.92), TCGplayer market prices via Scryfall.
As this enchantment enters, choose Sultai or Abzan. • Sultai — Whenever a counter is put on a creature you control, draw a card. This ability triggers only once each turn. • Abzan — Whenever you attack, put a +1/+1 counter on target attacking creature. It gains menace until end of turn.