The banshee?
Perhaps Dorn Beasts could be buffed by having the paralysation effect occur whenever it is visible to the PC (or a chance of occurring each turn it is visible, dependent on Wi)? As it is, Dorns are not nearly as dangerous as you would expect for a monster that has a warning. Or have a Medusa which instantly petrifies any PC who sees her.
Liches and Wyrms use a glowing balls attack, maybe other magic users could use these (and make them a bit tougher or harder to resist)? As-is, most of the higher level magicians just summon loads of crap which is a bit tedious. Fire giant kings have a pretty mean thrown attack, it would be fitting for other giants to have these as well.
Gate closers: L+ DE Mindcrafter (p20), N= Gnomish Assasin (p20), N= Gnomish Mindcrafter (p23), N= Ratling Ranger (R49)