Tom already knows that normally animus attracts mana, but when summoning that wizards use mana to attract animus, so with all his excess mana would it be possible to attract greater quantities of animus, which could then be used to attract mana, in a loop format as he siphons mana from his surrondings. Also it was mentioned that mana is most expressed when feeling strong emotions and that necromancers like fear. Would a demon stealing a God’s power cause enough people to fear him to gain a noticeable increase in his mana?
Demon’s are just animus bound to a manabody, so if a mage could summon sentient animus and bind it unwillingly to a manabody, a demon should be able to summon non-sentient or excess animus in ones surroundings and insert it within themselves. People pick up more of simply by experiencing new things and travel, so it shouldn’t be to hard to acquire.