I wonder if someone could answer this question I have concerning the Soul Sister deck.

I have a Suture Priest and a Leonin Relic-Warder in play.

Do I need two Phyrexian Metamorph to activate the infinite life combo, or one is enough? (exiles itself so come back, and exiles itself again...)

Thank you for your help.

one
it exiles himself when he come on the battlefield