Q 151: Aside from specific instances where they spell out a monster's associated classes (like they do with the Verdant Prince in MM4), is there any sort of guideline for what is and isn't an associated class for different creatures, other than "if it enhances it's combat ability, for a melee monster, it's associated," etc?
I'm building some Half-fiend and Fiendish trolls, and putting 4 levels of Warlock on a Half-Fiend Ice Troll for only +2 CR just seems dirty, especially when I give him Hideous Blow. Now he can fly around, cover my party with Darkness (and see just fine, thanks to Devil's Sight) and blast my party with Mortal Bane'd Eldritch Blasts...
And taking 10 on UMD checks to auto-activate wands seems dirty too...