Seer is not OP

To put it in perspective on some reasonings why people are saying Seer is Overpowered (yours truly as well), is that he is an amazing counter character without much effort; he hard-counters Mirage via heartbeat and the current glitch, while still trading with one of the best counters (Revenant) with the same passive; He also helps nullify Bangalore's tactical, hard-counters Octane, and (from what i hear, no testing has been applied yet from my end so take it with a grain of salt) soft-counters Gibraltar's faster resurrections, Lifeline's resurrections and tactical, pathfinder's tactical, Loba's tactical, Valkyrie's tactical (while launching), and Bloodhounds tactical.

He forces a slow, passive playstyle, which is harmful for some team compositions; It doesn't help that he has better Wallhacks than the other two Recon-wallhack characters, bloodhound and Crypto, with his entire kit being based around them; finally, his counters are more akin to checks, as Revenant doesn't like not being able to rush with his ultimate and Crypto not being in a good place right now, with Horizon the only true counter.