A fun thing that replaced mythic mobs, but generates lots of questions. If anyone has info to add or corrections to my info please do so below. Basically there is a chance for mobs around you to spawn as infernals, mini boss types that have a wide variety of abilities and will be noticeable by the flaming sparks and smoke around them. Note that they can even be passive mobs as I have seen a infernal polar bear (I was not in a cold biome at the time) and others have reported infernal rabbits. You will get messages like, "You hear a faint scream" which seems to indicate within your local chat range is a infernal, "watch out" seems to be closer, perhaps 50ish blocks and if they are closer still it will say "you hear a infernal zombie/etc nearby. If you are on the surface, it could be the mob is in a cave/ravine/unlit mine beneath you somewhere, and vice versa if you are mining. Loot obtained from the infernals does not adhere to your typical items or enchant restrictions, seeing things with say unbreaking 10 or mending 5. They also drop shields and charms that can give you a special boost if worn or held in hand, like a power boost you would get from a strength potion or ability to poison mobs. No longer in effect as of 8/6. Its important to note that unlike drops from mythic mobs you can generally add enchants to this gear as if had no enchant, so if you find a good item and are using it, you probably want to add mending or such. You can also salvage off very strong enchants from the gear but say you acquire Protection 10 on a book, when you try to add that to a piece of armor it will only give the item prot 4. In my experience the higher thorns does not actually seem to do more than thorns 3 but fortune 4 does seem to do more than fortune 3, you will have to experiment to see whats actually giving more or worthwhile bonus for you. Tips: When fighting a infernal, ranged is your friend, a good bow will make you less likely to be one shot or heavily damaged, you may still be blinded, poisoned, affected by thorns but hopefully you have a chance to eat/drink a pot if needed. Good armor is obvious but if you need more help consider using wolves as well. Edited 8/6/16 for change to charms/shields affects.