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