Well, @lipe, thinking about challenge, since mages are the most cheesiest possible characters, a non mage party is actually a helluvaparty. It has been one of the hardest pieces of game I've ever played, cause every mage slain was a conquest - can you ever imagine yourself disrupting the enemy lines with a non magic damageable character?
I'm sure I'm using my clerical habilities MUCH better after that, not to mention party tactics.
Irenicus? How did I beat him? Traps, lots of traps, wizard slayer front, high regeneration from potion on him, very high thac0. No hits until his flame shield goes down, and then use him as bait for the assassin traps. Boooom. Irenicus down!

Well, his friends have been previously engaged, of course.
Now Tactics is way more hard. Stopped playing this party for one FMT run. Will engage Tactics this way again soon... very soon.
Flesh to stone ain't permanent, it seems.