Name: Oni Possession Cost: 2B Type: Enchantment -- Aura Rules Text: Enchant creature At the beginning of your upkeep, sacrifice a creature. Enchanted creature gets +3/+3 and has trample. Enchanted creature is a Demon Spirit. Set/Rarity: Champions of Kamigawa uncommon, Duel Decks: Divine vs. Demonic uncommon, Duel Decks Anthology: Divine vs. Demonic uncommon Price: $0.16

Name: Onulet Cost: 3 Type: Artifact Creature -- Construct Pow/Tgh: 2/2 Rules Text: When this creature dies, you gain 2 life. Set/Rarity: Antiquities uncommon, Foreign Black Border rare, Revised Edition rare, Summer Magic / Edgar rare, Fourth Edition Foreign Black Border rare, Fourth Edition rare, Masters Edition common, Masters Edition IV common Price: $0.34

Name: Onyx Goblet Cost: 2B Type: Artifact Rules Text: {T}: Target player loses 1 life. Set/Rarity: Shards of Alara common, Salvat 2011 common Price: $0.09

Name: Onyx Mage Cost: 1B Type: Creature -- Human Wizard Pow/Tgh: 2/1 Rules Text: {1}{B}: Target creature you control gains deathtouch until end of turn. (Any amount of damage it deals to a creature is enough to destroy it.) Set/Rarity: Magic 2012 uncommon Price: $0.26

Name: Onyx Talisman Cost: 2 Type: Artifact Rules Text: Whenever a player casts a black spell, you may pay {3}. If you do, untap target permanent. Set/Rarity: Ice Age uncommon Price: $0.33

Name: Oona's Blackguard Cost: 1B Type: Creature -- Faerie Rogue Pow/Tgh: 1/1 Rules Text: Flying Each other Rogue creature you control enters with an additional +1/+1 counter on it. Whenever a creature you control with a +1/+1 counter on it deals combat damage to a player, that player discards a card. Set/Rarity: Magic Online Promos uncommon, DCI Promos rare, Morningtide uncommon, Jumpstart uncommon, Zendikar Rising Commander uncommon Price: $0.39

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: $0.22

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: $0.26

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: $2.10

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: $0.30

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: $0.11

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: $0.09

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: $0.16

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: $0.18

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: $0.23

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: $0.46

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: $4.12

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: $37.07

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: $0.15

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: $0.24