From Dota 2 Wiki
- Projectile launch sound plays as the attack projectile is released.
- Projectile impact sound plays as the attack projectile successfully hits the target.
- Play Loop sound plays permanently on Necrophos, gets louder while moving (50% vol).
- Play whenever Necrophos steps with his staff of the ground (30%-60% vol).
- Play Cast sound plays on Necrophos upon cast (80% vol).
- Play Cast sound plays on Necrophos upon cast .
- Heartstopper Aura does not use any sounds.