When you are running nightmare, hell and inferno modes in D3, you really need to know what you are going up against, because sometimes those yellow rare mobs can pwn you, ez pz.
Here is the list of rare monster affixes which will explain in better detail what the rare monsters will do when you come across them while playing Diablo 3.
Arcane Enchanted – Monsters enchanted with Arcane Enchanted trait deal additional arcane damage and have the ability to summon orbs which fire rotating arcane beams
Avenger – When a Champion group imbued with Avenger arrives, the death of each group member imbues the remaining Champions with added power/size as they wreak their frenzied vengeance on the Hero
Desecrator – A monster with Desecrator trait creates a glowing void zone beneath the targeted hero that damages the hero. Desecration will activate a few seconds after it appears on the floor, giving you time to get out of the void zone. (Darksaiyan)
Electrified – A monster with the Electrified trait has higher lightning resistance, deals additional lightning damage and discharges sparks across the floor in random directions when stuck.
Extra Health – This trait bestows the imbued monster with extra HP
Fast – This makes monsters run, attack and cast magic faster
Fire Chains – Champion backs are attached by a fire chain. The Hero suffers damage if he touches or even gets near one of the fire links.
Frozen – Monster with the Frozen affix can summon frost orbs that grow and eventually explode causing cold damage and applying a Chill and a Freeze debuff
Health Link – Health Link reduces the amount of damage taken by the champion with that trait by linking his HP to that of all other Health Link champions in the area
Horde – Horde increases the squad of minions that spawn with a rare monster, crowding the battlefield
Illusionist – The Illusionist trait imbues a creature with the ability to create clones of itself at much lower health levels
Invulnerable Minions – Monsters imbued with this trait arrive with a squad of indestructible puppet minions and an expanded heath pool
Jailer – This trait gives monsters the ability to immobilize the Hero in a conjured prison
Knockback – Knockback allows monsters to push back the player a short/long distance with each connecting blow, whether it be ranged or melee. Also, slows player. (OMGBBQLOL)
Missile Dampening – Creatures imbued with the trait generate a reddish sphere around themselves. Any projectile entering this sphere moves 90% slower than normal
Molten – Monsters that spawn with this trait deal extra fire damage. In addition, they leave trailing pools of lava that deal fire damage over time. Any non-minion monster killed with this trait leaves a time bomb that will explode after 3 seconds, dealing large amounts of fire damage
Mortar – Monsters with mortar can lob several fireballs that deal splash damage on impact. Mortar lobs a burst of 3 fireballs towards the player, even over obstacles, but will always lob over a character in melee distance. (Darksaiyan)
Nightmarish – Nightmarish monsters have a chance to fear the player on hit and can be triggered from both melee and ranged attacks
Plagued – Monsters enchanted with Plagued leave pools of poisonous green goo around them for 9 seconds
Shielding – This trait gives the monster a brief period of invulnerability to all forms of damage. Shielding mobs have green glow around them before they activate the shield. (Darksaiyan)
Teleporter – Gives the monster the ability to teleport to a nearby location
Reflect Damage – When you strike a Reflect Damage imbued foe with any attack, you suffer automatic damage in return
Waller – Monsters with Waller can summon earthen walls between the player and the monster, or sometimes behind the player to prevent escape. Waller mobs are different between elites and champions. Elite (boss with minions) create a box around the players to keep them in a general area, while champion packs create single walls in front or behind the player. (Darksaiyan)
Vampiric- This trait allows monster to literally feast on the damage they inflict to you by turning it into health for themselves
Vortex – Grants the ability to forcibly pull the player right next to the monster but does not pull player through objects.