The Onyx Dragon, Onikisu is a powerful dragon necromancer available via the Onyx Dragon Tower from events and promotions. Like other dragons, it is unable to be healed by Healers.
When a unit dies nearby the Onyx Dragon, it will resurrect that troop as an Onyx Dragon Whelp, similar to the Necromander. It will resurrect a maximum of 4 Onyx Dragon Whelps at a time.
Note that not much information is available on these troops because of a lack of information from Space Ape.