I'm just wondering what such a culture even wants in other galaxies.

If they can make energy out of basically nothing (Vacuum energy) and have 'sufficiently advanced technology that's indistinguishable from magic'... what business do they have in screwing around with other galaxies? Don't they have better things to do? I mean, any culture that can do that realizes that the universe is going to suffer from heat-death eventually. If they have effectively unlimited power, why are they wasting time goofing about in the universe instead of fixing the heat death problem? 

Edit: I don't think such a culture would even think on the same level as any other culture. They should have different things to think about aside from 'more land' 'more energy' 'more smarts' and whatnot. I doubt they actually used up everything in their home galaxies. Life has a fundamental aspect; it won't do shit it feels like it doesn't actually need to. If they have multiple galaxies, I doubt they have 'regular' problems we can relate to. What other problems could they have?