The Tipping the Scales Add-on for Orcs Must Die! 3 has 6 achievements.
Beat all "Tipping the Scales" scenarios
Kill 250 Tuatara
Purchase one upgrade for any "Tipping the Scales" gear
5 Skull one "Tipping the Scales" scenario on Endless
Kill 1000 Tuatara
5 Skull all "Tipping the Scales" scenarios on Rift Lord