Sorry- i got a bit lazy with this part. The following is only assumption; i assume that he takes this to burn through weapon ammo prior to fights to setup his weapon line to his liking EX. crescendum and severum, however, i cant confirm this because of the lack of content SKT T1's Teddy has available. Yes, essence reavers passive provides mana on hit but this doesn't apply when you aren't hitting anything EX. burning ammo with Q on the way to lane, however personally I don't find mana as too much of an issue so I typically run triumph anyway.