I have two, and haven't found a use for either. But I'm also considerably more endgame than you. If you find a use for him, I'm all ears :)

I agree.  I will certainly let you know if he helps at all.

Not a ton of flattering content on old Holsring out there. 

https://youtu.be/AHO0KWCsKMw

Caveat to this being this is a super, super endgame account which is hitting incredible stats BUT I do think there are some comps he can work in with regards to end game ones (Seer/reset/Lydia at least), and I think in a more normal, less end game comp he can do work in FK. The question just comes down to investing in him and whether it makes sense for most, which I have my doubts on. Then again, I undervalued getting set up for the FK grind early to mid game and it definitely has hurt me down the road when trying to piece together Savage/Regen/Immu sets.