Who wins?
By entire, I mean EVERYTHING. Halo, for example, would have all of the Precursors, Forerunners, Covenant, Flood, and Humans all teamed up against ALL the Star Wars universe
They all have their technology as well. Halo has their Halo Rings and such, Star Wars has all their Star Destroyers and Death Stars and all that
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The flood would infect anything that would die giving halo universe an overwhelming force (pun intended) to deal with. And if that doesn't work forerunners could compose the Jedi. And if that doesn't work the covenant and forerunners could team up and surprise glass Star Wars planets. And if that doesn't work the unsc could strategically place havoc bombs. And if that doesn't work the forerunners could create an Ark far from the Halos and remote detonate them.