Naberius was an apprentice to Archmage Vargoth. Kael'thas Sunstrider attacked Kirin'Var Village due to their close proximity to his Tempest Keep, as most of them were members of the Kirin Tor. Kael'thas used every thing he could to destroy the village, including a mana bomb. Archmage Vargoth was trapped in the Violet Tower since Kael'thas wasn't strong enough to kill him. All but Vargoth died in Kirin'Var. Naberius always talked about necromancy and he used this attack to betray his master and his "friends" and didn't allow their spirits to find peace. Naberius since then has turned into a lich and has hidden his phylactery (a bane to liches, such as himself) in the middle outhouse behind the inn. He is now located in the churchyard in Kirin'Var, and his device for manipulating the villagers' spirits can be found in the barn. Adventurers should seek out Ravandwyr, another apprentice to Vargoth, if they wish to try to kill this lich.
He mind controls ([Chains of Naberius]ωτϖ) the person whoever is the highest on his aggro list. Note: He does not mind control when only one person is on his aggro list.
He is immune to kick, stun, and disorient effect and slowing effects from like Frostbolt or Cone of Cold.
He has an AoE spell called [Lesser Shadow Fissure's] Consumption which every few seconds, does exactly 1000 damage each time. You can avoid this by stepping out of its radius.
The two ghosts near him will not aggro when Naberius is pulled, unless you get close to them.
His spells can be easily avoided: when he starts casting, go behind the corner.
Overall his melee attacks hit for 300-400 and frostbolts for 500-600, not much harder than a non-elite of this level, and his shadow fissure is easy to avoid. Appears not to have that much health either. Don't let the 3 man advice scare you. He can easily be 2-manned and most classes can solo him without too much problems.
Though it is not explained precisely how he became a Lich, one can assume that he corrupted his own soul and body when corrupting the dead villagers.