Yrleen, Child of Astrality

When this card comes into play, destroy target enchantment. Whenever a friendly creature is
tapped by a convoke, you may deal 1 damage to
target creature. Whenever this card attacks, you
may choose to instead use the active ability of a creature in your exile.
The other Sister I know is Yrleen, who seems to be
the one responsible for the creation of Astrality, and all
of it's wonder. So I guess that makes her the most
powerful of the two Sisters. Wait, what do you mean
there are three of them?