Sultai Runemark is a common Enchantment — Aura card from The List (PLST), collector number FRF-86. Current market price: $0.14, TCGplayer market prices via Scryfall.
Enchant creature Enchanted creature gets +2/+2. Enchanted creature has deathtouch as long as you control a green or blue permanent. (Any amount of damage it deals to a creature is enough to destroy it.)