Conclave's Blessing is a common Enchantment — Aura card from Ravnica: City of Guilds (RAV), collector number 11. Current market price: $0.19 (foil $0.39), TCGplayer market prices via Scryfall.
Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.) Enchant creature Enchanted creature gets +0/+2 for each other creature you control.