Feeding Grounds is a common Plane — Muraganda card from Planechase Planes (OHOP), collector number 9. Current market price: $1.49, TCGplayer market prices via Scryfall.
Red spells cost {1} less to cast. Green spells cost {1} less to cast. Whenever chaos ensues, put X +1/+1 counters on target creature, where X is that creature's mana value.