Balrogs will be spawned starting from a depth of -1800.
They are extremely powerful (HP: 200-600; Damage: 20), thus will be very rare.
If you manage to defeat one, it may drop a fire whip.
You can tune this mod through Settings/Advanced Settings/Mods/mobs_balrog
This mob was originally developed for the Lord of The Rings Game, I've just made it a separate mod.
Worked on 5.4
Really cool & tough mob. Don't know if I would attempt fighting this thing on a survival server.
The current version (0.4.0) officially only supports up to Minetest 5.1. But I was able to run it on 5.4 with just a few warning messages. Didn't seem to have any other problems.
You shall not pass
Make sure you are well kitted out with armor and weapons before going anywhere near this guy.