Githyanki Dark Urge is horribly unsatisfying... (Act 2 Spoilers)

[Lue]

ACT 2 SPOILERS

Running my second playthrough, I'm about 25 hours deep & in Act 2 with an evil Durge Githyanki. Needing to rely on hirelings to fill during Act 1 was already underwhelming (the only companions which made sense were Lae'zel and Astarion; I kept Gale until my other companions agreed he should bugger off with his chest nuke), but I powered through to experience more of this style of playthrough, along with wanting to experience Minthara (though she herself feels a bit awkward: you have to make a lot of evil decisions to access her, yet she's not particularly evil the moment you can recruit her and seems to be seeking redemption).

Anyway, finally got through Shar's trials with the aim of killing the Nightsong and fulfilling my Durge quest against Isobel... all to find out that only Shadowheart can kill her. A character who was hostile to me for being a Gith and whose corpse is currently laying in Act 1 as a result. I was trying to find another way to kill the Nightsong myself, but there doesn't seem to be... I'm hoping I'm wrong though! (And low-key reaching out for solutions.)

This isn't the first time I've run into issues with this playthrough either. The last major one was not being given the quest to kill Isobel. I helped her get kidnapped, spent an hour in tactician difficulty defeating the Shadow Curse event, only to long rest and being forced to kill one of the only 3 companions who I'll have for the rest of the play through. I reloaded.

I'll admit some of this disappointment might come from some preconceptions about where things 'should' go (unlike the untrod-snow of the first playthrough), but even considering this, I feel the game would benefit a lot if the evil-er paths were plumped up a little during the inevitable BG3: Definitive Edition.

[Mizu]

You aren't a Shar worshipper so why would she give you the blessing of Shar to kill her?