1300987:Sivandra has Will of the Forsken and her power reads: When Sivandra enters play, draw a card, then destroy an ally in your party.
If Sivandra is the only ally in my party, do I destroy her or does will of the forsaken save her?
Also if I have two more allies with Will of the Forsaken, do I destroy one or do they all stay in play?
That is correct, however if you 'did' have an ally in place without Will of The Forsaken you would have to destroy them you could not simple choose a WoTF ally for her effect unless the only allies selectable all had the effect. Basically, if you 'could' destroy an ally for her effect you 'would have too' if you cannot you simply play her and get your card draw.