I want to find a way of doing it this time without frustrating myself.

Seeing as I did it last time a solo priest with melee favored build, Indeed I had a problem.

The things you have to attack cause this caster to wipe the floor with your melee char. Isnt there another way of getting past her and just meleing her to death. I last time attacked the floor and she killed me 42 times with reloads on and off.

I just want to go about this better this time. Any thoughts?

Uh, we're referring to the final boss of SoU?

Kill the section of the mythal that's glowing to make her vulnerable and then attack her?

What part are you having trouble with exactly? If you want to email me your save (balkothwarcraft at gmail dot com) I could make a video of it.

The easiest way to beat the Heurodis fight is to use the Necklace of Fireballs (found near the end of the interlude) to quickly blast her power source. Once that's done, she's just a squishy caster who can be easily beaten down in meleee. If you don't have the Necklace of Fireballs, you should still be a high enough level to cast flame strike as a Cleric, which could be used to blast the mythal quickly.

The best way to deal with all casters in NWN is to use knockdown.
Hit once when they're down and then knockdown again.