The fire parts are the candle in the leftside of tower, fireplace in the left side, another fire thing(i forgot) on the left side up the stairs, and the torch in the middle bottom of the tower you jump down and you have to jump and bite it
How to beat challenge 4-Get two bots with best Chassis and Plating, then get the best Gun(not the hammer) then when the battle starts click and drag your units to follow the weaker enemy, then do the same for Sabertooth and you will win