Delta 360° is the invitation-only tier above Delta Diamond Medallion that includes many of the same perks as Diamond, plus some enhancements to make for a better travel experience. To get Delta 360° you need to spend a significant amount on Delta tickets or have control over corporate travel arrangements where you can influence spend toward Delta Air Lines.
Perks include:
Special phone line with highly trained agents
Complimentary Delta Sky Club Executive membership
More chances of Porsche transfers at hub airports
More upgrades on Delta flights thanks to higher upgrade priority