Monster Skill

Monster Skills are skills or spells used by monsters.

Diablo II
Monster skills may include combat spells and skills, but also self-affecting buffs or monster spawning abilities such as Lay Egg.

Some monster skills are modified versions of character skills such as Firebolt. However, some monsters (most notably Act Bosses) have unique abilities that are not available to players.

Diablo III
Diablo III introduces many new monster skills, although they are more commonly called monster affixes. Normal monsters do not have affixes, but Champion, Rare, and Unique monsters do. Bosses and Unique monsters often have unique affixes that are not listed here. Some Rift Guardians utilize empowered affixes, modified from their standard appearance.

In the list below,  yellow  affixes can only spawn on Rare Monsters,  blue  affixes can only spawn on Champion Monsters, and white affixes can spawn on either. The following affixes are seen in Diablo III:
 * Arcane Enchanted: Arcane enchanted monsters summon pulsing orbs of energy, which, after a brief delay, transform into rotating beams.
 * Avenger : Monsters with the avenger affix grow in power as other monsters in their group are slain.
 * Desecrator: Desecrator monsters conjure burning pools of hellfire beneath your feet.
 * Electrified: Electrified monsters release bolts of electricity when struck, causing Lightning damage on contact.
 * Fast: Fast monsters move and attack much more quickly than their normal counterparts.
 * Fire Chains : These monsters are periodically linked together by chains of fire that burn anything they touch.
 * Frozen: Frozen monsters create the ice crystals on the ground that damage and Freeze heroes.
 * Frozen Pulse: Monsters with the Frozen Pulse affix summon an icy sphere that chases the player. Once it comes into close proximity with a target, it stops and starts pulsing, dealing heavy Cold damage with each pulse every second.
 * Health Link : Monsters with health link share damage and Life pools. Any damage dealt to an individual is split among all members of a group.
 * Horde : Hordes of monsters don't gain any particular abilities, but groups with the horde affix have larger number of Minions than normal for their type.
 * Illusionist: Illusionist monsters create duplicates of themselves.
 * Jailer: Monsters with the jailer affix can encase you (and your followers) in a prison, slightly damaging and temporarily immobilizing you.
 * Juggernaunt : Juggernaut monsters are immune to crowd control, but take more damage from attacks and move slower to compensate.
 * Knockback: Successful hits from monsters with knockback send you flying away from them.
 * Missile Dampening : Missile dampening monsters project an aura that slows your incoming projectiles.
 * Molten: Molten monsters trail burning lava wherever they walk and explode upon death.
 * Mortar: Monsters with the mortar affix lob volatile globes of fire that can deal extreme damage to you at range.
 * Nightmarish: Successful attacks from nightmarish monsters can cause you to lose control of your character and flee.
 * Orbiter: Orbiter monsters summon electric ball clusters consisting of a central (large) ball and several smaller spheres orbiting the central one. These balls electrocute anything they touch, moving slowly, but dealing heavy Lightning damage.
 * Plagued: Plagued monsters can summon toxic puddles anywhere on the battlefield.
 * Poison Enchanted: Poison enchanted monsters summon toxic globules that fully form after 3 seconds and spread in a cross pattern, leaving a trail in their wake that causes significant Poison damage over 6 seconds.
 * Reflect Damage: Monsters with this affix deal a portion of the damage they take back to their attackers.
 * Shielding: Shielding monsters can conjure a temporary magic shield that makes them completely immune to damage.
 * Teleporter: Monsters with the teleporter affix can disappear and reappear in different locations on the screen at will, both to make surprise attacks and to escape.
 * Thunderstorm: Monsters with the thunderstorm affix can summon a lightning that hits the player (and all of their allies nearby) for a considerable amount of Lightning damage over a few seconds, with small intervals.
 * Vortex: Monsters with the vortex affix can pull you towards them, interrupting your attacks and keeping you dangerously close. Think of it as of reverse-teleport.
 * Waller: Monsters with the waller affix create walls that can trap you or block your path to the monster summoning them.
 * Wormhole: Monsters with the wormhole affix tear a pair of magical rifts in the battlefield. After several seconds, the wormholes emerge, and all heroes near one wormhole are teleported to the other.