
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.)
Phyrexian Unlife has 3 printings, first in New Phyrexia (2011). EDHREC ranks it #6,722 among Commander cards. It appears most in Zur the Enchanter decks (5,254 on EDHREC). It has 4 official rulings.
Deck counts from EDHREC.
Cards that show up in the same decks on EDHREC.