The easiest way to eliminate the Armor Troll guarding the entrance to Thorn's Throne Room is to have Chilla use his Ice Spear and knock the far chandelier from the ceiling onto the troll. When you climb up the ice wall near the end of the level,
do not jump down onto the battle arena. From the ledge you have a view point of the Large Battle Troll looking as if he is taking a nap. Set Chilla up so that you can see all the chandeliers and aim for the one farthest away. When it drops, it is a one hit kill and his club opens the entrance to Thorn's Throne Room.