The orb that is seen in the raid slot in the Rise of Iron page holds SIVA. You have just defeated the Machinist and two -blam!-ing S.A.B.E.R. shanks. You walk up to the orb and you are directed to destroy a large cube that is SIVA's new core... but then Vex come in and steal the cube just as its health reaches 0.04% health. You instead have to fight a Vex Overmind that broke off a piece of the SIVA core and stuck it in himself. You have to fight the SIVA Vex Mind in the orb and once you defeat him... you beat the raid. This kickstarts Destiny 2.