If you have unlocked the slayer perk, Bigger and Badder, you are going to come across superior slayer monsters on some tasks. One of these monsters that spawn superior slayer monsters are Nechryaels. They spawn Nechryarch. This is a pretty strong superior, who has the backup of 3 chaotic death spawns that each attack with a different combat style. If you aren't paying attention or if you do not have a lot of hit points left, you can easily get sent back to Lumbridge in under a minute.  The best way to kill them in my opinion is by using ancient magic. If you do not have some good food on you, you will need to use a blood burst or blood barrage spell. If you hit them, the spawns, and any other Nechryaels around, you can out heal the damage you get dealt pretty easily. It is advisable that you bring at least a single shark in case you have bad luck with your hits.  You can kill them with melee, but you are going to have to use quite a lot of food. If you do not have food with you and one spawns, I am going to suggest to you that you just run away or try to bank as soon as possible and try to make it back with food. If you are fighting without food, you are going to die, even at maxed combat.   I advise you to not attack the chaotic death spawns at all. Focus everything you have on the Nechryarch and kill it as soon as possible. The death spawns will despawn automatically once you have killed the superior slayer monster.