Generator Servant is a common Creature — Elemental card from The List (PLST), collector number M15-143. Current market price: $0.30, TCGplayer market prices via Scryfall.
{T}, Sacrifice this creature: Add {C}{C}. If any of that mana is spent on a creature spell, it gains haste until end of turn. (That creature can attack and {T} as soon as it comes under your control.)