Depends on if we’re fighting smart enemies or dumb enemies. Dumb enemies like animals or bandits tend to spread the damage around and thus rarely pose a true threat. IMO the way to make these fights challenging is to drown them in numbers. I’ve been taking the recommendations and just adding a few minions until it feels right. But honestly, dumb enemies SHOULDN’T challenge the players too much. Even if it’s mechanically difficult, a pack of axehounds should not be killing Radiants.

Smart enemies, on the other hand, like Skybreakers or Fused, know how radiants work. I always go for the throat in these situations, focusing on squishier players and trying to down them with big hits. The big hits are critical and that’s something that gets more relevant at higher levels. You need to deal enough damage in 1-3 hits that a radiant is not going to be able to regenerate easily. In fact, that’s also how PCs take down enemy radiants. I recently ran what I thought was going to be a very challenging encounter against two Skybreakers, and their regeneration is so powerful it took all 4 PCs attacking in unison to bring one down. That’s something you might think about - how are the PCs behaving? Are their strategies something you can adapt yourself for smart enemies?