This is a fun thread. I'd actually like to get a composite of a couple of the ships mentioned with something from the World-as-myth series from Heinlein. Let's say the body of a Bird of Prey, that planet destroying cannon mentioned upthread, and the Burroughs continua device as motive power. Think about it. Pop! there it is in front of you, it fires that big cannon, pop! it's gone and you're toast. Oh, your sheilds held. No matter, Pop! it's now behind you and firing again, disappearing as soon as it has. You've no chance to shoot back, as it doesn't even stay in the same universe after it fires.

Talk about invincible.