Devil May Cry HD Collection

You wont unlock devil trigger until you beat mission 7. After you have done that, you can buy Purple orbs from Divinity statues or the customizer at the mission start screen. Buy all 7 puple orbs to unlock this achievement.

Purple orb prices:

1. 3000
2. 5000
3. 7000
4. 9000
5. 10000
6. 20000
7. 30000

This adds up to a total of 84,000 orbs. A good way to farm red orbs is by replaying and earning an S rank on mission one on easy mode. By doing this you can earn 5000+ orbs every roughly every minute with little to no effort.