Purple Worms
As someone has mentioned, the best way to kill purple worms is the
"DM two-step" (moving sideways, turning 90 deg., etc) in a 2×2 square.
DO NOT run away, DO NOT use doors (these approaches don't get you any
experience!), DO NOT waste magic on them (your characters usually won't
have enough mana at this point). Go real slow, and attack only one pair
of them at a time. Put two fighters up front with axes. If you do it
right they won't even get hit. When I use the DM two-step on worms,
I kill one of them so fast the other one runs away and I have to go
chase it. Beautiful sight. I have killed the dragon with one character
doing the DM two-step – it works.
– kn