The Demon Knight keeps killing my leader with fire before I can attack him with the rest of my party. I have checked posts on this web page and they talk about a chess game in the tower, I can't find it. Need help.

If your leader is getting killed when the DK first shows up during the "tour", trying using a potion of fire resistance on him or have one of your spellcasters try protection from fire.

The "chess board" is much further into the tower. Be patient ... you will get there.

Or just stand aside, the demon always shoots his fireballs to the same place

Or for hours of frustration, try to KILL the DemonKnight. I have a screenshot where I shot about 35 Arrows of Detonation into him--you actually can't see the DemonKnight because the fireballs are so thick, you can only see a little glimmer where he's casting a spell. It still wasn't enough to kill him, though. I'm going to try again today or tomorrow....using Arrows of Piercing/Acid this time.

WELCOME TO THE BOARD, BY THE WAY!!!

Arrow of Biting always works on mages. At least is usually do.

Poisoned weapons, such as the Arrow of Biting, are EXCELLENT against Mages, or indeed any enemy. If the poison rate is high enough, they can't even take a swing at you, they have to keep wincing from the poison.

But that's IF they fail their Save vs. Death. And I think the Demonknight has all his Saving Thows at 1. I've used a Wand of the Heavens on him, for a whopping 3 Damage, because he always Saves vs. Wands. It's insane. So on this try, I'm setting 6 Skull Traps (I think I sold 4 other Skull Trap scrolls during the course of the game, and I could also have bought the ones at High Hedge, so I think I'll hack about 8 more into my Inventory and still be able to call it halfway-fair) and then having my Hasted archers go nuts with Arrows of Ice (no Save) or Acid (doesn't say if it allows a Save or not) and my Druid cut loose with a Necklace of Missiles. Maybe I should also have my Thief stand just out of range of the Skull Traps and hope for a Critical Hit Backstab Quadruple Damage.

Killing the bad guys is a lot tougher when they only stick around for less than 3 seconds.