Although Bruce learned the many weakness that the demon had, the situation didn't solve itself. Agaruth still was possessing Angeline, so he couldn't attack. Bruce had enough mana to use a few spells, but he doubted that it would be enough.
Agaruth – Lv 20
HP: 710/ 1280
MP: 800/1660
SP: 890/900
However, at some point, Bruce noticed it. Agaruth didn't use SP until now, but his SP decreased just like his magic. In that state, to gain a boost of power, it was obvious that he would have to sacrifice something, and that something was his energy. His attacks still used magic, and using his body to fight would consume stamina, so eventually, he would be too weak to keep Angeline under his control. The problem was: would Bruce be able to resist until that happens?