Umm I don’t know if this is correct but I belive a passive would work well a idea I made was called hunter ”in the face of someone weaker then you, the user receives a 20% increase in speed, in the face of someone stronger your will recives a 15% buf”
Draw a NZT - 49 pill. NZT 49 has all the same positive effects NZT - 48 has and is non addictive. it also slowly grows the brain to allow it to be permanent. he will only have to take a few dozen to no longer need taking them. it is also a way to allow him to grow his mind but not to fast.
I think he should perfect the consumption learning ability. He could slowly start removing the penalties it has, each removed penalty would make the ability a magnitude better than before.
A [Concealment] skill would be good, it can hide his presence, and his smell. And for it to work, it spends 2 mana per second (Example).
Another good skill would be [mana regeneration]. It converts physical resistance into mana.