Necro is great for exploring most areas, if you can log long enough sessions to have big zombie armies.

Evil conjie is also very good for exploration if you have an imp. You can regear with pretty nice stuff too. For example, my regear consisted of killing the mobs at the top of Calandryl (for neckwear) and the lich in barovia for pitted iron, and robe. Used archangels for this. Just takes a bit of setting up. And for the lich, you want your familiar to engage first so that you don't eat the entry prog.

Conjie can also tess to his familiar, or other mobs, or phase door, or just walk past as the familiar fights.

Master of dismissal or whatever it is means that you can dismiss with pretty much 100% effectiveness if your mobs get nasty. Although I did tend to have lots of mana.

Now that scion is gone, I'd probably favour the necro over the conjie.

Muter is arguably the best for pk. Can be a bit crappy for exploring areas where the mobs are immune to your spells. Not sure if it is still the case, but mass spells used to work on things where the non-mass version didn't.