Necromancer's Magemark is a common Enchantment — Aura card from Guildpact (GPT), collector number 53. Current market price: $0.21 (foil $0.48), TCGplayer market prices via Scryfall.
Enchant creature Creatures you control that are enchanted get +1/+1. If a creature you control that's enchanted would die, return it to its owner's hand instead.