For anybody who wonders how it screwed up, I have a theory: OCR.
魔物 - monster
魔 - demon
天使 - angel
使い - user (tamer, in this context)
What you should see: 魔物使い - monster user
What (alleged) OCR saw: 魔天使い - demon angel
Though to get it this far off in the final product seems to imply a lack of quality checking, a lack of English ability, or a lack of reading comprehension. Nobody looked through the product, and was able to realize that something was out of place. Alas, such is the world of scanlations nowadays. OCR into MTL, and much prayers. Not much thoughts. But thoughts and prayers to all y'all readers.