SG probably thought hard about this one and from a revenue perspective she is great for SG because she pairs perfectly with new Voidstar (tough portal too with lower odds but double joy if you do hit the jackpot, so a big money spinner), older but still desired Shaal and Sha and now the slightly oxidized Aramis. Shame the satisfaction of an average player appears not to have been part of the thought process.
If you have them Grilka is a great support for her mana generation bonus and taunt (spend to get her), if you accidentally get her (ahem, I did), then the incentive is to summon for the others (guilty in Astral).
As a standalone hero she does not feel useful, only with that narrow slice of heroes. Rustbeak on the other hand seems very well designed for actually being used, shame RB is just a 3*.
Sigh.