beholders fall to right equipment, and undead are pathetically easy, have a high level cleric turn them. with aerie or anomne, they blow up so fast its pathetic.
mind flayers are very bad, very deadly, but htese days I have perfected the planetar with globe of blodes up and running. even if it gets held or stunned, this happens a lot, the globe will keep killing them. for a nasty nest have cleric cast free action, this makes them invulnerable.
but still nothing gets me worried than a nest of flayers. very bad, sorta remind me of a xcom mission, and you're boarding a etherial battleship.
They call me Darth...