Phylactery

Phylactery enters the battlefield with X vitality counters.
Your life total becomes 0 and your life total
cannot change.
You don't lose the game for having 0 or less life.
For each point of damage you would suffer,
instead remove a vitality counter from
Phylactery.
At the beginning of your upkeep, if Phylactery
has no vitality counters, destroy Phylactery.