Kodama's Might is a common Instant — Arcane card from Champions of Kamigawa (CHK), collector number 224. Current market price: $0.22 (foil $0.42), TCGplayer market prices via Scryfall.
Target creature gets +2/+2 until end of turn. Splice onto Arcane {G} (As you cast an Arcane spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card's effects to that spell.)