Errant Minion is a common Enchantment — Aura card from Ice Age (ICE), collector number 68. Current market price: $0.16, TCGplayer market prices via Scryfall.
Enchant creature At the beginning of the upkeep of enchanted creature's controller, that player may pay any amount of mana. This Aura deals 2 damage to that player. Prevent X of that damage, where X is the amount of mana that player paid this way.