Manacles of Decay is a common Enchantment — Aura card from Apocalypse (APC), collector number 14. Current market price: $0.05 (foil $0.80), TCGplayer market prices via Scryfall.
Enchant creature Enchanted creature can't attack. {B}: Enchanted creature gets -1/-1 until end of turn. {R}: Enchanted creature can't block this turn.