Together nothing can stop us.
The problem with your intial idea is that you are saying that you are invincible for them. You are positioning yourself as a threat that can't be overcome, challenging them and at the same time insulting their abilities by mocking that they won't ever be able to be on par with you.
You can say something like your initial idea to a third party in secret to explain your plan if you are trying to win them over by demonstrating your powers in front of the opposing party. In that case your sentence works perfectly to convey the idea and explain your actions, but you have to make sure never to say something like that directly to the party you are trying to win.
Working together is a great thing and nobody ever needs to know that you think you are better than them. You just want them to join you so that both of you can profit from this and be more powerful than before.