For the sake of this match the galaxies will be seperate but at a near distance or else it would be too far for certain factions to travel to an opponent's home galaxy. Hell we can say that several wormholes connect both galaxies to make it easier. Anyway the problem is that the star wars forces have to find the rings first. It's impossible because of the following reasons: -These rings can be anywhere in the entire massive galaxy because they are mobile, more likely they will be sitting in extragalactic space near the arks -Space is massive trying to locate a location is nigh impossible Both Halo and star wars side have to figure out the locations of eachothers populated planets. They can do that by spying on eachother communication chatter (if they are able too). The easy way is too steal the nav database of a starship. The Halo side has multiple ways of stealing a starship like making the use of supression fields to immobilise said ship and board it, or AI's can use extract data from the onboard computers. Forerunners had an advanced sensor that could scan an entire small galaxy for civilisation, it was in silentium where the librarian and her crew visited one of the magellanic clouds. I'll reread these chapters later for more info.