Racaxis, cursed Jackal

Lifelink
Racaxis enters the battlefield with four -1/-1
counters on him.
Whenever you gain life, you may remove a -1/-1 counter from Racaxis.
{1}: Put a -1/-1 counter on Racaxis.
{3}{b}{b}: Target player loses life equal to the
number of -1/-1 counters on Racaxis. Activate this ability only once each turn.