| Name | Cost | Price |
|---|---|---|
| Omnipresent Impostor | $0.49 | |
| Omniscience | $7.07 | |
| Omnivorous Flytrap | $0.27 | |
| Omo, Queen of Vesuva | $0.48 | |
| O-Naginata | $0.48 | |
| Onakke Oathkeeper | $0.60 | |
| Once and Future | $0.26 | |
| Once Upon a Time | $1.37 | |
| Ondu Giant | $0.11 | |
| Ondu Greathorn | $0.23 | |
| Ondu Inversion // Ondu Skyruins | $1.25 | |
| Ondu Knotmaster // Throw a Line | $0.16 | |
| Ondu Rising | $0.05 | |
| Ondu Spiritdancer | $15.67 | |
| One Does Not | $15.00 | |
| One Dozen Eyes | $0.23 | |
| One Last Job | $0.23 | |
| One with Nature | $2.82 | |
| One with the Kami | $0.40 | |
| One with the Machine | $0.25 | |
| One with the Multiverse | $2.39 | |
| One With the Wind | $0.08 | |
| Ongoing Investigation | $0.22 | |
| Oni of Wild Places | $0.41 |