Here is the full list of all 12 BloodRayne Betrayal achievements.
Hop on 50 heads in a row without touching the ground
Activate BloodRayne: Betrayal's alternate soundtrack
Kill 5 enemies with a single gunshot
Chain-explode 5 enemies
Collect all the ancient vampire skulls
Complete the game
Finish every level with the ranking "Dhampir"
Complete any level while taking no damage
Kick open the Coffin Rocket 20 times
Find the hidden idol
Defeat Crab Puncher without getting hit
Kill 250 enemies with environmental hazards