Well I think scouting and pinpointing enemies is a valid tactic, Cloudkill wipeout of unaware enemies I'm not so struck on and I never leave a battle via a screen change once the ruck starts. It's do or die. To be honest I don't do a lot of magic anyway, usually holding (web, entangle) or healing spells is about my limit excepting the occasions where mass very tough opposition is encountered, then fireballs or C.K may be the order of the day. I'm soloing with a pure thief at the minute so loads of magic isn't really an option. I say solo but I will take a companion for quest purposes, currently it's Jaheira and we just took out Mencar Pebblecrusher and chums after many reloads. My thief is only level 10 presently but my main tactic is stealth, highlight enemy and then archery to take them out. It doesn't always work as you can get swamped but haste and invisibility potions help a lot. I don't think C.K'ing a blind unaware enemy horde is a lame tactic, if you have been stealthy, reconnoitred the enemy positions and then sent the Napalm in then that's fair enough. It's exactly what happens in real warfare, none of the "show us the whites of yer eyes" these days. If that's what you want to do, if you enjoy doing it and that's how you progress in your game then there's nothing wrong with that whatsoever.
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It's bleedin dark down here, slippery too.

Man, that's a pisser.