Castle Darkmoor was easier than expected, when just speedrunning it. Just clicking the cube to activate the last cube, and taking the backdoor to the last cube, and jumping down close to the last cube. As to not land right on the Lich King. I would have no chance against his army. Even at level 57 (I'm level 60 now).
And now I'm really struggling with the Tomb of Varn, as speedrunning doesn't work (way too many enemies!). And slowly taking out enemies is difficult, as the Guardians of Varn (the highest tire of the Anubis-like creatures) are immune to air. And I'm still using sparks, as I found a ring to boost air magic in Paradise Valley, so it makes it extremely difficult, as they absorb the sparks for other enemies in a group of enemies.
Damn, I guess it will take quite a lot of time.
And this is the thing with this playthrough: I just found that it takes longer. It doesn't add some unique challenge. Other than just "getting the achievement" of having done my first 2-player party. Still I have to say, it has been more interesting than playing a full party. As it changed up the ordering of quests and made some minor differences all around.