Helia, dark Sorceress

If you spent {b} to cast Helia, target opponent
may sacrifice a creature. If he or she doesn't, Helia enters the battlefield with a +1/+1 counter.
If you spent {u} to cast Helia, target opponent
may have you draw two cards. If he or she
doesn't, Helia enters the battlefield with a +1/+1 counter.
At the beginning of your end step, if Helia's power is 2 or more, transform her.