Someone will probably bring up that stat scaling buffers would be the dominant strategy here. Loop and buff up to 1000 stats in the early rounds and then just go for as long as possible. The problem is this would be stale after just a few tries.
I think a mode like this would work better if it wasn’t “endless” and about how far you could get, but rather something enough to be a battle long enough where attrition could be a factor so you’d want to be conservative about making trades and build a team that can go the distance but doesn’t need the extended looping stat buffing setup to be entirely frontloaded. Say, a few dozen troops, scaling into a bit higher than what an average PvP battle would be. Maybe throw a boss at the end of it.
I think Arena has a good solution to the idea of an infinite run. The game goes on until you either lose twice or win a fixed number of times. For a mode that isn’t limited-pool like Arena, I think maybe a nice idea would be “you can choose 8, 10, or 20 matches and stats scale each match”.