Okay. I'll save that other device for later. It won't be as OP (Plus I'll modify it until then) at that point either. Your'll see why, ;)

As for the nanobot syringe... good one! Perhaps after these bots enter into your stream, your body detects them as a virus and starts to destroy them. Any future attempt at using them simply makes your body destroy them almost instantly (Since they won't fight back.) Alright... now onto the problem of the monster. He's still targeting the two twins, how do we get him to not kill them? Unless we want him to kill them... so they can never be reused.