This is just purely a curiosity question on my part....
What's the point of having her have so many hit points that you must beat on her repeatedly for 15, 20, 30 minutes over and over again? I've seen fights in other games last that long, and have never personally seen the attraction. In my opinion, it is like a long-winded stalemate that eventually turns into a win on one side or the other.
Please understand that, again in my opinion, the circumstances are different from a battle I participated in in DAoC (I think it was, might have been EQ). There the battle waged on for that long, but the creature (a dragon perhaps?) had abilities that would teleport people out of combat range (basically toss you back to a "bind point"), would kill any and all in a tight melee range with a PBAOE, and various abilities like that. It made the half hour (plus) long battle have people coming and going constantly, times when different characters were needed in close (or far away).. The challenge always was can the right people be in the right place at the right time to take the creature down. Wish I could remember details better, but unfortunately old age has set in and I only have vague recollections of who I played the game with, not who it was we were fighting.
So back to the original question... What would the point of giving her tens of millions of hit points be but to keep a group in one place for a long period of time playing "wack a mob" while the healers kept them alive?