You can visit your necromancer platform and see if you have a ranger or mage head you could try with your creature. Leveling early in the fjords, before heading to Sentinel Island, I found my creature much more helpful trying to take out some imps with a level 2 ranger head than he was with a level 6 warrior head (I switched to a mage head as soon as I found one).
Did you try standing inside one of the healing chambers? That should block his access, and force him to run for the opposite chamber.
If you wait awhile and avoid combat, do summoned walking armours build up enough to help slow or block Raze's movements?
A belated welcome to the forum.
