problems with retreating SuperCombatant

[Whismerhill]

I'm having a problem with my supercombattant

he seems to be creating armies or controlling some ennemies sometime and then these units are killed and my supercombattant retreat

actually the supercombattant is :
R'lyeh void lord :
-empowered to 10 in all magic path,
-lucky coin
-enchanted sword (of no use I think but not sure)
-rainbow armor
-boots of the behemoth
-amulet of resilience
-snake ring
(along with gift of health global enchantment)

I'm fighting in an ennemy dominion

actually it can totally wracks tons of atlantian units but I have difficulties keeping him on a fortress cause of that retreating problem ...

does anyone has the same problem or now of a way to force commanders to stay in battle ?