Melodriia, the Dreamgale

Astral Convoke. (You may only tap friendly
creatures to pay this card's cost) When
this card is killed, instead exile it. This card may
be played from the exile as if from your hand.
Many Astral beings choose a Knowledge Seeker to
follow and learn from. Choosing someone as your Knowledge Seeker lets them impart their unique
knowledge to you, for example you can learn truesight
from Aeon. Melodriia's knowledge is of the Dreamgale.
She never speaks though, so no one knows what it is.