Cheapest priced copy (Wilds of Eldraine: Enchanting Tales): $0.79 at Card Kingdom, near mint, their price list as of .
Phyrexian Unlife 
Enchantment · Rare · New Phyrexia · #18
You don't lose the game for having 0 or less life.
As long as you have 0 or less life, all damage is dealt to you as though its source had infect. (Damage is dealt to you in the form of poison counters.)
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
3 printings · $0.79 to $10.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| New Phyrexia | 18 | Rare | $0.99 | $10.99Out of stock |
| Secret Lair Drop | 1213 | Rare | — | $9.99 |
| Wilds of Eldraine: Enchanting Tales | 11 | Rare | $0.79 | $1.49 |
4 rulings from Wizards of the Coast
- 1 June 2011If you’re at 0 or less life and Phyrexian Unlife leaves the battlefield, you’ll lose the game (unless some other effect is keeping you from losing).
- 1 June 2011You can still lose the game for other reasons, including having ten or more poison counters or drawing a card from a library with no cards in it.
- 1 June 2011If you’re at 0 or less life, you can’t pay any amount of life except 0.
- 1 June 2011Phyrexian Unlife won’t affect damage that reduces your life total from a positive number to 0 or less. For example, if you’re at 3 life and are dealt 5 damage, you’ll end up at -2 life. The next time you’re dealt damage, it will be dealt as though its source had infect.