Ashenbone drakes are "belly caster" mobs, you have to be within melee attack range to land spells on them, except perhaps for unresistable spells. They are undead, and they are necromancers. They are noteworthy for the decrepit hide they drop, used in the Shadowknight Epic 1.0 quest, Innoruuk's Curse
Like all mobs in Plane of Hate, these can spawn almost anywhere in their tier of the zone. These inhabit Tier 1 of Plane of Hate and can be static or roamers, indoors or out.
They have a very small "hit box" so you have to be very close to attack or cast. They can quad but spend about half their time casting. They do not bash or kick or bite or any other melee attack but hit. They do not summon, enrage or rampage.
As necromancers they cast spells like Venom of the Snake, Asystole, Invoke Fear, Scourge, Root and lifetaps. Although they are necromancers they do not seem to ever summon pets, as most pet class NPC in Plane of Hate do not summon pets.
They cast spells a fair amount of time. Meleeing or using pets seems the best strategy against this particular mob unless you're well enough geared to stand toe to toe with it while you try to cast spells and hope to channel through the interruptions.