616 Terrax The Tamer
vs
LOSH Imperiex
This is the cosmically empowered Terrax. The one who served Galactus during Byrne's run.
Imperiex for the LOSH cartoon isn't the galaxy busting final boss from Our World At War. The below video gives an idea of his level. Can tank blows from a Superman and toss him around.
Neither characters have morals. So this is to the death.
All weapons and abilities are at the user's disposal. Imperiex is a machine. So BFR into space won't affect him.