How do you get the Grumish Greataxe to appear?
If you want to summon the Grumish Greataxe, do the Hall Servant quest. Then you will have to defeat Bort Malletmane. Then you have to do the Vault of Ice again. Finally, you can light the braziers in the Entrance Hall and summon the Grumish Greataxe and his two minions.
Where are the braziers in the entrance hall?
the braziers are around the circle in the entrance hall, just go around and look for something that looks like a pot with 3 legs.