Cheapest priced copy (Phyrexia: All Will Be One Commander): $16.99 at Card Kingdom, near mint, their price list as of .
Phyresis Outbreak 
Sorcery · Rare · Phyrexia: All Will Be One Commander · #50
Each opponent gets a poison counter. Then each creature your opponents control gets -1/-1 until end of turn for each poison counter its controller has.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
2 printings · $16.99 to $17.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Phyrexia: All Will Be One Commander | 12 | Rare | $16.99 | — |
| Phyrexia: All Will Be One Commander | 50 | Rare | $17.99 | — |
One ruling from Wizards of the Coast
- 4 February 2023The amount a creature's power and toughness are reduced is determined only once, at the time Phyresis Outbreak resolves. It won't change if that creature's controller later gets more poison counters or if another player takes control of it later in the same turn.