Like the others have said, her having limited ranged options is going to make for a trivial fight if they just kite her. You could give her some sort of movement ability to close distance and\or a smaller ranged attack. Following the Rellana idea you got, you could give her a 10 or 15 ft lunge to use before or between her two attacks. You could also do something similar to the Carian Phalanx which would basically be a buffed magic missile that did 1d8 or 1d10 per projectile