use a dedicated server

It says "addon too new to use old API"; is there a way to fix this?

You can mess with math.random (and one way to do that is by seeding the RNG, which this addon blocks). If you really want to mess with math.random you can override that function in a similar to how I overrided the math.randomseed function, but that will break all users of the RNG in Gmod, so I'd highly recommend against that.

yeah, what i meant was math.random, but i guess this one can't be messed with

Probably not, this addon only changes the math.randomseed function and the item you were talking about doesn't use that function.

could this finally possibly break the qtg invincible npc?