There are some tough characters (Kostyan, Kornuel, Igbah, Fatfrumos, e.t.c.) whom you cannot kill. So NEVER fight them alone (even if you have to reraid from them). NEVER fight in a group against group with any of those characters within. If you fight as a group against 1 of them - ALWAYS use archon (not angel) and always cast dispel magic on them as many times as needed to dispel their preps (only aura, barrier and shield cannot be dispelled - even dispeling their enlarge can win a battle for your group).

You can use angel and preps against weaker enemies, but i wouldn't recommend it. ALWAYS use archons and spend last points of your constitution for exploring (because conjurers are very good at it and you'll need this knowledge for your future characters). Try to find how to regear your future characters at different levels.

Nobody expects you to kill evils. But we all expect that as goodie conjurer you shouldn't die at all!

Few years later after playing many different classes you can attemp to play conjurer again and it will be VERY different game.