Ebonblade Reaper
Creature — Human Cleric
Whenever this creature attacks, you lose half your life, rounded up.
Whenever this creature deals combat damage to a player, that player loses half their life, rounded up.
Morph 
(You may cast this card face down as a 2/2 creature for . Turn it face up any time for its morph cost.)
Wayne England
Onslaught (ONS)
• #141Rulings
If you attempt to halve a negative life total, you halve 0. This means that the life total stays the same. A life total of -10 would remain -10.
(wotc • 2007-02-01)
Rulings
If you attempt to halve a negative life total, you halve 0. This means that the life total stays the same. A life total of -10 would remain -10.
(wotc • 2007-02-01)