Hour 37: Halted by Howling Cave

I roam through the countryside for a while, looking for creatures to battle. In the countryside to the east of Skingrad there seem to be a fair few trolls. Panicked at first (it's been a while since I've seen one), I relax when I see the ease with which my new custom spell (which I've labelled 'Punisher'...) brings them down.

Eventually I come upon Howling Cave. It looks fairly ominous:

What on earth is that glowing cauldron? I head inside and am initially disappointed as it appears to be populated by nothing but rats. However, when I head into the deeper levels, I see that it's a haven for necromancers. Well, better them than vampires I suppose. Unfortunately, they seem to outmatch me. At one point I open a door and two necromancers await me, as well as a couple of skeletons, and both the necromancers summon headless zombies. Try as I might, my own Skeleton Guardian is cut down in moments by the throng, and I am constantly forced to retreat. I can't get past the press of undead in the narrow corridors to get to the Necromancers behind them (in hindsight, I should have used by Repulse Undead spell... but I forgot about it) and even if I can get a spell through to them, they heal faster than I can damage them. I give up and decide to have a think about creating some different spells.

After checking online, it looks like the Weakness to Fire in my spell is largely wasted, as it doesn't combine with the initial damage. Since I only made the Weakness last 1 second, it would only come into play if they get damaged again by fire within 1 second. This likely happened to the trolls, since I summoned my Atronach to aid me, but often would be wasted. It seems that there are more efficient ways to create damaging spells. I also think it might be worth finding and adding a 'paralyse' effect into a damaging spell.