Skinks will often kill the annoying beast, but if his save is too high, say like a Star Dragon, all of those beasts usually have a low Initiative. Due to this, I take a decked-out Slann and hide in some woods so the Dragon can't hit me, then give him LoS with a FSoD cept it's a Priest. When all that's done, roll however many times it takes for Pit of Shades, and if you get it early, might as well try for the Beast lore, I believe there's one spell that renders monsters worthless in combat nad outside of combat.
Also Kroxigors help ALOT if you take Shadow and use Unseen Lurker to ensure they get the charge. And nice thing about Pit of Shades is that if he fails his probably low initiative, it dies instantly, no matter what. Just remember, usually about 3 units of blowpipes at 10 per unit can bring it down. Also, JSoD works WONDERS, just make him immune to psychology and highest armor save you can manage and smack the beastie around!