I was wondering how I could check for a radius around the player, so that I can sort any living entities into a list? The concept is I want any living entities that come in a specific radius of the player to be set on fire.

Get the player's bounding box, make it bigger (grow, expand), and there are a couple methods in World called getEntitiesWithinAABB or something similar where returns a collection of entities that meets the conditions.

If you want it to be more accurate (bounding box is a cube), you can also check the distance between two entities by Vector3d#distanceTo.

Hmm, I'm guessing getEntitiesWithinAABB doesn't exist in the 1.16 version because I can't seem to find the method?

It's probably called something else in mojmap compared to the mcp name provided. A quick search using the forge bot lands us with World#getEntities.

Ok, so I did find this method called getNearbyEntities and started playing around with it, but I'm having trouble figuring out what to put in the place of some of these parameters

getNearbyEntities(Class<? extends T> p_217374_1_, EntityPredicate p_217374_2_, LivingEntity p_217374_3_, AxisAlignedBB p_217374_4_)

I had already gotten that AxisAlignedBB is just the bounding box aka the radius to check and I just assume EntityPredicate could just be the default, but the other two I'm unsure about if anyone could explain?

Appreciate all of the help, got what I needed working.