Multiattack.The devil makes three attacks, using Searing Fork or Hurl Flame in any combination. It can replace one attack with a use of Infernal Tail.
Searing Fork.m 10, reach 10 ft. ({@damage 2d8 + 6) Piercing damage plus 9 (2d8) Fire damage.
Hurl Flame.r 8, range 150 ft. ({@damage 5d8 + 4) Fire damage. If the target is a flammable object that isn't being worn or carried, it starts burning|XPHB.
Infernal Tail.dex 17, one creature the devil can see within 10 feet. 10 ({@damage 1d8 + 6) Necrotic damage, and the target receives an infernal wound if it doesn't have one. While wounded, the target loses 10 (3d6) Hit Points|XPHB at the start of each of its turns. The wound closes after 1 minute, after a spell restores Hit Points|XPHB to the target, or after the target or a creature within 5 feet of it takes an action to stanch the wound, doing so by succeeding on a 17 Wisdom (Medicine|XPHB) check.