Who was that red priestess?

[One-eyed Misbehavin]

Is she more powerful than Mel? She seemed at least as confident as Mel. 

[Uncle Benjen's]

She's meant to be the High Priestess, the equivalent to the High Septon/Sparrow I imagine so one could say she is probably more powerful AND older than Mel

[Bran the Shipper]

For some reason I always got the impression that Mel is kind of a rogue priestess and not a good representative of the actual order.  For instance I don't get the impression that any other priest/priestess is older than they appear, though I could be mistaken.  Kinvara (the new red priestess) is head priestess of Volantis, so in terms of internal hierarchy she is higher up than Mel, but I don't think she is as powerful.  Mel is from Asshai and is a trained Shadowbinder so in terms of magic she likely would run circles around Kinvara, but Kinvara might know secrets of the Red Faith that Mel isn't privy to.

[Hol Horse]

She ain't shit. Not till she shows somethin'. Feats are what matter; talk is cheap, and everyone's got a plan until they get shanked by a shadow-baby.

 

[Good Guy Garlan]

She's the High Priestess, so like Benerro in the books, and we still don't know the extent of his powers. Other than a glowsticks display, he still hasn't really done anything, much less something as impressive as a shadow baby or bringing people back from the dead. 

[BalerionTheCat]

She is Benerro in the books, the High Priest of Volantis. Not sure if she is shadowbinder like Mel. But she is the highest known authority over Red Priests, everywhere in the Known World. Not sure for Yi Ti and Asshai.

[DanïelNorth]

Knowing about a certain private ritual implies she can look into the past.....

[permaximum]

The First Servant of the Lord of Light title speaks for itself. Speaking about Varys' origin even more in detail than himself can remember is surely a sign of what's to come from her