Saethtra, Devourer of Minds

When Saethtra, Devourer of Minds enters the battlefield, choose a player. That player discards
2 cards and loses 2 life.
{u}{b}{t}, Pay X life: Draw X cards and put X +1/+1 counters on target Nightmare you control.
Nightmares you control get +2/+0 and have indestructible.