Very simplified and my own accord, but I always grouped decks by thier lands.
Bazzaar ( dredge, survival, or Welder/Reanimator/Dragon)
Forbidden Orchard (oath)
Cavern of Souls ( lions and tigers and bears)
Tolarian Academy (combo)
Library of Alexandria (control)
In general if I look at a list, and it has these lands,in the appropriate shell of, that is what it is. I'm honestly surprised no one else groups this way. The lands you run are the key deciding factor to what deck you are playing, not the win con or draw engine.
If I were to build a solid Karn based deck in Vintage, I would start with:
4 Sai, Master Thoptist
2-3 Skull clamp
Restricted Blue/Artifact stuff (tinkerbot/tv optional)
And go from there. Obv about infinite splashes after this point, but I'd use that as the core, and see what you have room for from there. Would be glad to discuss this tho. Keep this updated. Thanks!
How often in Vintage is this gonna hit more than 1 thing outside of Tokens? 2 sphere's maybe? But this seems very hard to cast through multiple sphere's, so idk what it would even be used for. Reflector Mage and Counterspell Spirit both seem better in the same colors, and better creature type. As well as Jailer already mentioned.
Just the simple fact that the player who has this in play first gets to play thier Fow/Gush/MM for free while the other cannot is so powerful an effect. Even if your opponent has all the removals, if you get to fire off MMs while they are tapped out with multiples in hand, ugh? I honestly like the "can't play spells with cc>lands in play" clause, but the no free spells, one sided nonetheless, insane.
There goes any chance of my bounty of the hunt deck to work
I think if your splashing green anyways, Dr. Shaman should be in there. Can make turn 3 Amin more easily done. Also Manglehorn seems great since it stalls PO and can blink for CA vs any artifact style deck. I also think Sylvan Library is strong here. Have you considered or tried Stoneforge Mystic? Only needs blinked once to do some dumb things.