Welcome to Grimlock’s life. If you tell him he cannot do it, he will, and he’ll succeed. Impossible? Not in his vocabulary. You have a plan? He has two. One involves blasting your ass from orbit after sending out clones of himself to fight you. He very well could have taken you out, but why should he? You aren’t even worth his time.
Going up against Grimlock means not coming back. Just sit down and wait for the literal ass-whooping you are about to receive. No need to even try to fight back, it won’t be worth it.