I've been using this mod for a little over a month now and I was wondering if there would be an easier way to notice challenger mobs without getting close.

Though the only thing I can think of adding the potion particle effect on them. This might be no different to what a witch would look like when they use potions or the blaze particle effect might interfere since they have smoke particle effects on them. I think it would be best if you could get the effect that enchanted items. It help a lot when hunting for challenger mobs though.

I could make them glow?

That would make sure easy to spot, but it might be too intrusive since they can be seen through walls.

Unfortunately I don't know what kind of effects you can put on entities to come up with an idea.

Fair... I'll think on it a bit.

I decided to take a note of how Atomic Stryker's Inferno Mobs work, and add particle effects. Unlike inferno mobs, I've decided to set the color based on the challenger mob trait 😄

Brilliant, don't forget to add options to the config to enable/disable it.

Added config plus it follows the Game settings for particles (e.g. all, minimal)