Pulling the lever deactivates the nearest regeneration chamber (or at least it should, at least for a couple people they are
inactive in the US Xbox version). You should not need to pull both of them. Stand near one of the chambers, and that will be the one he goes for when his health gets down; if you deactivate that one (or block his path with your creature, summons and/or his summoned walking armours), he should not be able to make it to the other chamber (Rush Attack, a bow or magic should be able to finish him off).
General Raze how defeated?
