Here is the full list of all 8 Flight of the Paladin achievements.
Defeat all three bosses in Survival Mode in one playthrough
Hear all music in Survival Mode
Obtain a score of 10,000 Points in Survival Mode
Survive 60 seconds in Survival Mode
Complete the Campaign Stage "Ruins of the Count"
Defeat 100 Monsters in Campaign Mode.
Complete the Campaign Stage "The Hollow Road"
Complete the Campaign Stage "The Woods"