<font color="gold">Mordekainen's Sword works very well. None of the Illithid's attacks can harm them, and they are summoned for quite some time. [img]smile.gif[/img] </font>

Newbies! ;) ;)

There are a number of good ways to take down mind flayers without any serious risk.

As Sir Exxon stated, Mordekainen's Sword is excellent. Summon Undead is also excellent if the summoned undead is a skeletal warrior. Simple skeletons will die too easily.

Don't bother summoning elementals. They are really stupid and a single mindflayer psi attack will kill'em.

Keep potions of Genius and/or potions of mind focusing. Both add to your INT, thus "healing" INT damage taken fron mindflayer INT drain attacks.

Mindflayers always seem to umber hulks. Ignore the umber hulks untill all mind flayers have been killed. Keep your summoned allies focused on killing mindflayers.

As Arledrian mentioned, cast the priest spell "chaotic commands" on your 1 or 2 toughest tanks and send them into the melee. Keep your other party members well back initially until the mind flayers are fully engaged by your melee fighters and allies. Then you can sneak them up to provide long range missile and/or magic support fire.

Pay close attention to your melee fighters' INT. If they take INT damage, drink another INT enhancing potion or withdraw from the melee for a short time. INT drains only last for a few rounds.

Another note: Chaotic commands and the potions last for a good long while. So take advantage of this and try to wipe out the entire mindflayer complex all at once. You might need to summon replacement allies.

My favourite tactic is still hasted Skeleton Warriors.

I found that a few Invisible Stalkers will do the trick nicely, however if you'd prefer not have your party standing idle then Chaotic Commands is the only way.