| Painted Bluffs | AKH-246 |
| Painful Lesson | AKH-102 |
| Painful Lesson | BBD-154 |
| Pain Magnification | DIS-121 |
| Pact of Negation | A25-68 |
| Pack's Favor | GRN-139 |
| Pack Leader | M21-29 |
| Pacifism | M20-32 |
| Oxidize | P05-4 |
| Ox | TOTJ-3 |
| Owl Familiar | POR-63 |
| Ovinomancer | DMR-64 |
| Overwhelming Encounter | CLB-245 |
| Overrun | CMA-130 |
| Overgrowth | 9ED-262 |
| Overgrown Farmland | MID-265 |
| Overgrown Battlement | IMA-180 |
| Overgrown Armasaur | RIX-141 |
| Overflowing Basin | M3C-362 |
| Overcome | M20-186 |
| Outnumber | BFZ-150 |
| Outmuscle | ELD-170 |
| Outmaneuver | USG-205 |
| Outlaws' Merriment | ELD-198 |
| Oust | DDP-7 |
| Oubliette | 2XM-100 |
| Otherworldly Journey | DDC-16 |
| Ossification | ONE-26 |
| Orzhova, the Church of Deals | GPT-162 |
| Orzhov Guildgate | RNA-253 |
| Orzhov Enforcer | RNA-79 |
| Orzhov Basilica | C17-268 |
| Orzhov Advokist | C16-3 |
| Orvar, the All-Form | KHM-305 |
| Orochi Eggwatcher // Shidako, Broodmistress | CHK-233 |
| Ornithopter of Paradise | MH2-232 |
| Ornithopter | M15-223 |
| Ormos, Archive Keeper | JMP-13 |
| Orim's Chant | PLS-11 |
| Oreskos Swiftclaw | M15-22 |
| Oreskos Explorer | C21-98 |
| Order of Yawgmoth | DDE-11 |
| Order of Yawgmoth | USG-144 |
| Order of Midnight // Alter Fate | ELD-99 |
| Orcish Settlers | WTH-112 |
| Orcish Oriflamme | EMA-140 |
| Orcish Lumberjack | DDL-44 |
| Orcish Cannonade | DDN-28 |
| Orcish Artillery | 10E-220 |
| Orc Sureshot | FRF-78 |