In the campaign I'm playing in, there is internal conflict in the upper planes, and one of the lead instigators is a solar. We've killed it multiple times, but it keeps coming back with reinforcements. The party plans to go to the upper planes to finish it once and for all... But the DM says that it'll be stronger in its native plane.
Is this typically true – are outsiders stronger in their native planes? Is this true for other outsiders?
I'm fine if it's homebrew, but I'm just curious.