Crown of Suspicion is a common Enchantment — Aura card from Onslaught (ONS), collector number 134. Current market price: $0.10 (foil $0.55), TCGplayer market prices via Scryfall.
Enchant creature Enchanted creature gets +2/-1. Sacrifice this Aura: Enchanted creature and other creatures that share a creature type with it get +2/-1 until end of turn.