| Oak | |
| Obliterator | |
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Obscenery |
| Obscure | |
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Obsequies |
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Occult |
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Öde |
| Ominous Dark | |
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Omnihierophantom |
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Onheil |
| Onraad | |
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Onrust (Yawgmoth) |
| OP | |
| Opacity (Opacity Of Evil) | |
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Opacity Of Evil |
| Ophiuchus (Cloak Of Altering) | |
| Order Of The Source Below (Dodecahedron) | |
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Ordo Draconis |
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Orewoet |
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Ornaments Of Sin |
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Orodruin |
| Ostracised | |