Spark Double is a rare Creature — Illusion card from War of the Spark (WAR), collector number 68. Current market price: $9.98 (foil $11.20), TCGplayer market prices via Scryfall.
You may have this creature enter as a copy of a creature or planeswalker you control, except it enters with an additional +1/+1 counter on it if it's a creature, it enters with an additional loyalty counter on it if it's a planeswalker, and it isn't legendary.