There is a lot of personal choice you're excluding, and very little in regard to wars is rule/Imm defined.

All items belong to the emporer, so Empire should be vs all. (Yeah, you to spire!)

Good tribbies often fight empire out of City limits.

Outtie is often at war with Scarab, that whole lich as an inner thing and mummy leader.

Recently there was a Battle vs the world thing going down. Have a mage in your cabal, here, eat DBs inners.

Entropy, what did you say?