Rarin' to Go is an achievement in Diablo 3.
Kill 50 rare enemies of the following types[1]:
Savage Beast
Harvester
Imp
Enraged Phantom
Savage Fiend
Quill Demon
Scavenger
Skeleton
Skeletal Archer
Returned Archer
Arachnid Horror
Dark Berserker
Dark Cultist
Unholy Thrall
Disentombed Hulk
Hungry Corpse
Retching Cadaver
Ravenous Dead
Dune Dervish
Fallen Overseer
Fallen
Fallen Peon
Fallen Cur
Fallen Conjurer
Betrayed
Accursed
Cave Wing
Murderous Fiend
Vicious Ghoul
Lacuni Huntress
Lacuni Slasher
Dust Imp
Sand Dweller
Sand Behemoth
Ancient Walker
Reaper
Skeletal Sentry
Skeletal Raider
Bone Warrior
Spine Hewer
Skeletal Ranger
Smoldering Construct
Charged Construct
Noxious Guardian
Serpent Magus
Webspitter Spider
Brood Hatchling
Frenzied Hellion
Hulking Phasebeast
Demonic Tremor
Armored Destroyer
Herald of Pestilence
Demonic Hellflyer
Demon Trooper
Fallen Slavelord
Fallen Grunt
Fallen Soldier
Fallen Hellhound
Fallen Prophet
Blood Clan Warrior
Blood Clan Occultist
Wintersbane Huntress
Stygian Crawler
Skeletal Marauder
Skull Sword
Skull Cleaver
Soul Ripper
Succubus
Colossal Golgor
Darksky Fire Demon
Enslaved Nightmare
Mallet Lord
Subjugator
Armaddon
Morlu Legionnaire
Morlu Incinerator