Cheapest priced copy (March of the Machine Commander): $1.49 at Card Kingdom, near mint, their price list as of .
Soul of New Phyrexia 
Artifact Creature — Phyrexian Avatar · 6/6 · Mythic · Magic 2015 Promos · #231p
Trample
{5}: Permanents you control gain indestructible until end of turn.
{5}, Exile this card from your graveyard: Permanents you control gain indestructible until end of turn.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
7 printings · $1.49 to $14.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander 2016 | 274 | Mythic | $1.79 | — |
| Commander 2018 | 223 | Mythic | $1.79 | — |
| Commander Masters | 974 | Mythic | $1.79 | — |
| Magic 2015 | 231 | Mythic | $1.99 | $8.99 |
| March of the Machine Commander | 382 | Mythic | $1.49 | — |
| The List | M15-231 | Mythic | $1.49 | — |
| Magic 2015 Promos | 231p | Mythic | $1.49 | $14.99 |
2 rulings from Wizards of the Coast
- 18 July 2014You can activate the last ability only if the Soul is in your graveyard.
- 18 July 2014Exiling the Soul from your graveyard is part of the last ability's activation cost. A player can't remove the Soul in response to prevent you from activating the ability.