Razor's damage steal goes through magic immunity. For that reason he destroys Naix, who'll charge at you thinking he's immune and then you steal all his damage. Then the slow wears off and you casually chase Naix until he dies.
I know that static link persists through things like disruption, but does it break if naix infests a nearby creep?
Probably, but I don't know for sure. Everything else seems to be put on hold when Naix infests so it probably breaks.
He's an anti carry that does damage when you attack him but has almost nothing threatening about him. Without stealing someone's attack damage he does next to no damage and both his aoes are trash. One wants you to be far away for the max damage and one needs you close and it can also hit creeps.
If you build him tanky you can hit for any damage outside of stealing it and if you build for carry you're squishy as hell and is outperformed by other carries.
Glad you realized why Razor can be amazing. He can just be built as a regular tank and still deal insane damage, while rendering the enemy team's carry useless. He used to see a lot of tournament play before the meta changed to constant ganks, where he doesn't shine as much due to the lack of disables.