Wiki - Dominatable Undead
The first number refers to the number of pet slots a pet has when freshly dominated. The second is the maximum number of pet slots available through training. To train a pet, use Animal Lore on it. At the bottom of the gump there is a button to click to 'Begin Training'. Start this and then fight with the pet. When training reaches 100% then you may advance your pet by one slot and spend training points on it's abilities in the same menu. You will have to reopen the Animal Lore gump to refresh the progress bar while training. Every slot added to a pet increases the Minimum Necro Skill by 10. If training a pet would increase it's requirements beyond what the owner has then they will not be able to complete the training. The chance to control a pet is determined by both Necromancy and Spirit Speak, so it's important to have more than the value needed in both skills to ensure the pet stays loyal.
Some creatures are naturally violent and will attack you on sight, while others are peaceful. When confronted with a potential pet that wants to eat you rather than be friends, the best way to deal with the issue is by use of the Peacemaking skill. If the skill check works then it will calm the creature long enough to allow you to attempt to tame it. It should be noted that using Peacemaking does not prevent a creature that can anger on tame from doing so.
All Undead are hostile.
This is the minimum amount of Necromancy skill required to attempt to dominate the creature. The further above this number a characters Necromancy goes the more success that character will have in attempting to dominate it.
Some creatures have strong social ties with others of their kind. Pet owners benefit from keeping these creatures families intact. For each pet that shares a Pack Instinct after the first a 25% damage bonus is awarded from their attacks so long as they are attacking the same foe. This bonus caps at 100% with five pets. (Example: Two Black bears, A Grizzly, and Two Brown Bears may be used to attack one dragon and deal 100% more damage than normal.)
All Undead have the Undead pack instinct.
*The Red Death and Skeletal Mount are mountable.
** The Tomb Keeper is a humanoid, dressable, undead that can benefit from the gear and weapons it uses. If they die, equipped items will fall on their corpse. Insured items will not appear on the corpse, but may be recovered from a revived pet by using the 'Drop' Command from their context menu. There is no way to retrieve the corpse of a pet so, similar to creatures with packs, owners will need to recover these items manually. Max control requirement is 128 for this pet.
***The Kanashibari requires 120.9 Necromancy to dominate. Should it be trained to 5 Slots, it will require 128.