Name: Oona's Prowler Cost: 1B Type: Creature -- Faerie Rogue Pow/Tgh: 3/1 Rules Text: Flying Discard a card: This creature gets -2/-0 until end of turn. Any player may activate this ability. Set/Rarity: Lorwyn rare, Double Masters 2022 rare Price: $0.30

Name: Opal Acrolith Cost: 2W Type: Enchantment Rules Text: Whenever an opponent casts a creature spell, if this permanent is an enchantment, it becomes a 2/4 Soldier creature. {0}: This permanent becomes an enchantment. Set/Rarity: Urza's Saga uncommon Price: $0.23

Name: Opal Archangel Cost: 4W Type: Enchantment Rules Text: When an opponent casts a creature spell, if this permanent is an enchantment, it becomes a 5/5 Angel creature with flying and vigilance. Set/Rarity: Urza's Saga rare Price: $2.58

Name: Opal Avenger Cost: 2W Type: Enchantment Rules Text: When you have 10 or less life, if this permanent is an enchantment, it becomes a 3/5 Soldier creature. Set/Rarity: Urza's Legacy rare Price: $0.39

Name: Opal Caryatid Cost: W Type: Enchantment Rules Text: When an opponent casts a creature spell, if this permanent is an enchantment, it becomes a 2/2 Soldier creature. Set/Rarity: Urza's Saga common Price: $0.15

Name: Opal Champion Cost: 2W Type: Enchantment Rules Text: When an opponent casts a creature spell, if this permanent is an enchantment, it becomes a 3/3 Knight creature with first strike. Set/Rarity: Urza's Legacy common Price: $0.13

Name: Opal Gargoyle Cost: 1W Type: Enchantment Rules Text: When an opponent casts a creature spell, if this permanent is an enchantment, it becomes a 2/2 Gargoyle creature with flying. Set/Rarity: Urza's Saga common Price: $0.15

Name: Opal Guardian Cost: WWW Type: Enchantment Rules Text: When an opponent casts a creature spell, if this permanent is an enchantment, this enchantment becomes a 3/4 Gargoyle creature with flying and protection from red. Set/Rarity: Time Spiral rare Price: $0.23

Name: Opal Palace Type: Land Rules Text: {T}: Add {C}. {1}, {T}: Add one mana of any color in your commander's color identity. If you spend this mana to cast your commander, it enters with a number of additional +1/+1 counters on it equal to the number of times it's been cast from the command zone this game. Set/Rarity: Magic Online Promos common, Commander 2013 common, Commander 2016 common, Commander Anthology common, Commander 2017 common, Commander Anthology Volume II common, Commander Legends common, Kaldheim Commander common, Commander 2021 common, Neon Dynasty Commander common, Warhammer 40,000 Commander common, Commander Masters common, Modern Horizons 3 Commander common, Lorwyn Eclipsed Commander common, Secrets of Strixhaven Commander common Price: $0.16

Name: Opal Titan Cost: 2WW Type: Enchantment Rules Text: When an opponent casts a creature spell, if this permanent is an enchantment, it becomes a 4/4 Giant creature with protection from each of that spell's colors. Set/Rarity: Urza's Saga rare Price: $0.50

Name: Opal-Eye, Konda's Yojimbo Cost: 1WW Type: Legendary Creature -- Fox Samurai Pow/Tgh: 1/4 Rules Text: Defender (This creature can't attack.) Bushido 1 (Whenever this creature blocks or becomes blocked, it gets +1/+1 until end of turn.) {T}: The next time a source of your choice would deal damage this turn, that damage is dealt to Opal-Eye instead. {1}{W}: Prevent the next 1 damage that would be dealt to Opal-Eye this turn. Set/Rarity: Betrayers of Kamigawa rare Price: $3.51

Name: Opalescence Cost: 2WW Type: Enchantment Rules Text: Each other non-Aura enchantment is a creature in addition to its other types and has base power and base toughness each equal to its mana value. Set/Rarity: Urza's Destiny rare, World Championship Decks 2000 rare Price: $39.97

Name: Opaline Bracers Cost: 4 Type: Artifact -- Equipment Rules Text: Sunburst (This artifact enters with a charge counter on it for each color of mana spent to cast it.) Equipped creature gets +X/+X, where X is the number of charge counters on this Equipment. Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.) Set/Rarity: Fifth Dawn common Price: $0.11

Name: Opaline Unicorn Cost: 3 Type: Artifact Creature -- Unicorn Pow/Tgh: 1/2 Rules Text: {T}: Add one mana of any color. Set/Rarity: Theros common, Conspiracy: Take the Crown common Price: $0.13

Name: Open the Armory Cost: 1W Type: Sorcery Rules Text: Search your library for an Aura or Equipment card, reveal it, put it into your hand, then shuffle. Set/Rarity: Shadows over Innistrad uncommon, Secret Lair Drop rare, Commander Legends uncommon, Pioneer Masters uncommon Price: $2.39

Name: Open the Graves Cost: 3BB Type: Enchantment Rules Text: Whenever a nontoken creature you control dies, create a 2/2 black Zombie creature token. Set/Rarity: Core Set 2019 rare, Core Set 2019 Promos rare, Midnight Hunt Commander rare, Starter Commander Decks rare Price: $0.50

Name: Open the Vaults Cost: 4WW Type: Sorcery Rules Text: Return all artifact and enchantment cards from all graveyards to the battlefield under their owners' control. (Auras with nothing to enchant remain in graveyards.) Set/Rarity: Magic 2010 rare, Commander 2015 rare, Commander 2016 rare, Double Masters rare, Fallout rare Price: $0.34

Name: Ophiomancer Cost: 2B Type: Creature -- Human Shaman Pow/Tgh: 2/2 Rules Text: At the beginning of each upkeep, if you control no Snakes, create a 1/1 black Snake creature token with deathtouch. Set/Rarity: Commander 2013 rare, Commander Collection: Black rare, Historic Anthology 6 rare, Jumpstart 2022 rare, Modern Horizons 3 rare, Tarkir: Dragonstorm Commander rare, Secrets of Strixhaven Commander rare Price: $0.60

Name: Opposition Agent Cost: 2B Type: Creature -- Human Rogue Pow/Tgh: 3/2 Rules Text: Flash You control your opponents while they're searching their libraries. While an opponent is searching their library, they exile each card they find. You may play those cards for as long as they remain exiled, and you may spend mana as though it were mana of any color to cast them. Set/Rarity: Magic Online Promos rare, Commander Legends Promos rare, Commander Legends rare, Through the Omenpaths Bonus Sheet mythic, Marvel Universe mythic Price: $22.73

Name: Oppression Cost: 1BB Type: Enchantment Rules Text: Whenever a player casts a spell, that player discards a card. Set/Rarity: Urza's Saga rare, Seventh Edition rare, Secret Lair Drop rare, The List rare, Wilds of Eldraine: Enchanting Tales rare Price: $3.45