While playing around with abomination I found that using the node “Age of undeath” inside abomination skill tree (makes abomination not decay health and will only consume mages/skeletons) only works if you consume 6 or less total skeleteons/mages.
EDIT: more testing, found that it has to do with unspeccing skeletons and then speccing into rip blood. Attached a video of it. This only happens if summon skeletons as extra minions nodes taken.