Gleam of Authority is a rare Enchantment — Aura card from Dragons of Tarkir (DTK), collector number 19. Current market price: $0.37 (foil $0.57), TCGplayer market prices via Scryfall.
Enchant creature Enchanted creature gets +1/+1 for each +1/+1 counter on other creatures you control. Enchanted creature has vigilance and "{W}, {T}: Bolster 1." (To bolster 1, choose a creature with the least toughness among creatures you control and put a +1/+1 counter on it.)