O) Jerren, Corrupted Bishop

Whenever Jerren enters the battlefield or another nontoken Human you control dies, you lose 1 life
and create a 1/1 white Human creature token.
{2}, Tap X untapped Humans you control: Up to
one target creature gets -X/-X until end of turn
and you gain X life.
At the beginning of your end step, if you have
exactly 13 life, you may pay {2}{b}. If you do, 6/6>
transform Jerren.