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: $0.21

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 Price: $0.12

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: $0.51

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: $3.36

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: $28.51

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: $0.12

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: $0.14

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: $2.59

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: $0.49

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: $0.19

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 Price: $0.70

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 rare, Commander Legends Promos rare, Through the Omenpaths Bonus Sheet mythic, Marvel Universe mythic Price: $21.41

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: $1.64

Name: Oppressive Rays Cost: W Type: Enchantment -- Aura Rules Text: Enchant creature Enchanted creature can't attack or block unless its controller pays {3}. Activated abilities of enchanted creature cost {3} more to activate. Set/Rarity: Journey into Nyx common, Magic 2015 common Price: $0.05

Name: Optimistic Scavenger Cost: W Type: Creature -- Human Scout Pow/Tgh: 1/1 Rules Text: Eerie -- Whenever an enchantment you control enters and whenever you fully unlock a Room, put a +1/+1 counter on target creature. Set/Rarity: Duskmourn: House of Horror uncommon Price: $0.13

Name: Oracle en-Vec Cost: 1W Type: Creature -- Human Wizard Pow/Tgh: 1/1 Rules Text: {T}: Target opponent chooses any number of creatures they control. During that player's next turn, the chosen creatures attack if able, and other creatures can't attack. At the beginning of that turn's end step, destroy each of the chosen creatures that didn't attack this turn. Activate only during your turn. Set/Rarity: Tempest rare Price: $0.65

Name: Oracle's Attendants Cost: 3W Type: Creature -- Human Soldier Pow/Tgh: 1/5 Rules Text: {T}: All damage that would be dealt to target creature this turn by a source of your choice is dealt to this creature instead. Set/Rarity: Nemesis rare, Eighth Edition rare, Ninth Edition rare Price: $0.15

Name: Oracle's Vault Cost: 4 Type: Artifact Rules Text: {2}, {T}: Exile the top card of your library. Until end of turn, you may play that card. Put a brick counter on this artifact. {T}: Exile the top card of your library. Until end of turn, you may play that card without paying its mana cost. Activate only if there are three or more brick counters on this artifact. Set/Rarity: Magic Online Promos rare, Amonkhet Promos rare, Amonkhet rare, New Capenna Commander rare Price: $0.15

Name: Orah, Skyclave Hierophant Cost: 2WB Type: Legendary Creature -- Kor Cleric Pow/Tgh: 3/3 Rules Text: Lifelink Whenever Orah or another Cleric you control dies, return target Cleric card with lesser mana value from your graveyard to the battlefield. Set/Rarity: Magic Online Promos rare, Zendikar Rising Promos rare, Zendikar Rising rare Price: $0.16

Name: Orator of Ojutai Cost: 1W Type: Creature -- Bird Monk Pow/Tgh: 0/4 Rules Text: As an additional cost to cast this spell, you may reveal a Dragon card from your hand. Defender, flying When this creature enters, if you revealed a Dragon card or controlled a Dragon as you cast this spell, draw a card. Set/Rarity: Magic Online Promos uncommon, Friday Night Magic 2015 rare, Dragons of Tarkir uncommon, Commander 2017 uncommon Price: $0.20