A quick question about PM gameplay and tactics

[Sircowdog]

I understand that at some point at the higher levels, you start using web+wail to kill masses of monsters, but I'm still at the midpoint using a 2rog/18wiz build. I'm currently at 9th level wiz, levelling so far using Archmage until I hit lvl 12 and make the swap over to PM. Wraith form and the other nice perks that come with 12PM, such as necrotic bolt, should be nice.

But having never taken a caster to this level before, I'm starting to get into unknown territory for how it'll perform. Specifically I'm wondering how a PM deals with undead, especially those pesky blackbones that are immune to firewall. So far I've been using the blunt effect part of icestorm since I didn't feel like acid rain was doing enough(maybe I'm doing it wrong?)

I'm sure there's all kinds of enemies I haven't encountered yet that are going to give me fits. Ranged types are always annoying because they seem to have a habit of sitting just outside the range of my AOEs, although low cost spells like scorching ray, melfs, or MM take care of them quickly. But what about things like beholders? Are there any particular enemies I should be especially concerned about as I move into higher level content?

Also, if there's a guide for general PM tactics and strategy that I'm missing, just call me a noob and point me in the right direction. Not stuff like build strategy, but actually using the class during quests. I'm pretty sure I've got the basic to moderate skills of an arcane down pretty well, having solo'd longer quests like The Pit, Stormcleave, Tear of Dakaan, and the entire Co6 chain all on hard. What I need is more advice on specific and advanced techniques.

As always, thanks in advance!