Revenant
Demon Skeleton 
400 Hit Points
480 Experience Points per kill
Summon/Convince: 620/620
Abilities: Melee (0-180), Life Drain (30-60).
Pushable: 
Push Objects: 
Walks around: Energy
Est. Max. Damage: 235 hp per turn
Immune to: Fire, Poison, Life Drain
Neutral to: Physical, Energy
Sounds: None
Task: Experience Tasks
Field Notes: They are slow and rather unintelligent. This creature will retarget, kill weaker monsters and push objects to get to you. This is an excellent summon because its immune to many elements, its used a lot for hunting.
Location: Triangle Tower, Hellgate, Plains of Havoc, Thais Ancient Temple, Vilias Dungeon, Mintwallin, Drefia, Garrogat Hero Cave, Shadowthorn, Elvenbane, Ghostlands, Femor Hills, Isle of the Kings, Yehsha Tombs, Forgula, Daraman, entrance to PoI
Strategy:
With a weapon skill of 75, a Warrior can kill a demon skeleton with a Two-handed weapon and 0-2 Ultimate Healing Runes. If a Warrior is using a one-handed weapon, he/she can kill a Demon Skeleton on level 30 and skills 65/65 quite easily. Just bring a few UH's for safety reasons.
A Paladin could hunt these with a distance level of 60. Demon Skeletons are slow, so lower skills wouldn't be a safety concern; you'd merely waste too many bolts for the loot they give.
A Druid or Sorcerer use Heavy Magic Missiles. The Invisible spell is also useful and can save your life, since they can not see invisible creatures.
Loot: 0-40 gp, Guardian Shield, Mind Stone, Throwing Star, Battle Shield, Torch, Battle Hammer, Iron Helmet, Mace, mysterious fetish
Monsters