| Name | Edition | Colour | Type | Cost | Power | Rarity | $ |
|---|---|---|---|---|---|---|---|
| Once More with Feeling | UG | White | Sorcery | WWWW | Rare | 4.22 | |
| One Dozen Eyes | MI | Green | Sorcery | 5G | Uncommon | 2.03 | |
| One with Nature | SC | Green | Enchant Creature | G | Uncommon | 2.08 | |
| One with Nothing | SK | Black | Instant | B | Rare | 0.64 | |
| Oni of Wild Places | SK | Red | Creature - Demon Spirit | 5R | 6/5 | Uncommon | 0.20 |
| Oni Possession | CK | Black | Enchant Creature | 2B | Uncommon | 2.16 | |
| Onslaught | EX | Red | Enchantment | R | Common | 3.05 | |
| Onulet | RV | Artifact | Artifact Creature | 3 | 2/2 | Rare | 0.54 |
| Onulet | AQ | Artifact | Artifact Creature | 3 | 2/2 | Uncommon | 2.88 |
| Onulet | 4E | Artifact | Artifact Creature | 3 | 2/2 | Rare | 0.59 |
| Onyx Talisman | IA | Artifact | Artifact | 2 | Uncommon | 2.55 |