Step 1. While Crota is being summoned sacrifice an exotic in the name of the sun. Once you clear out the enemies in the crystal room a vex star gate will spawn and Atheon steps out and starts to fight Crota. Step 2. While Atheon and Crota are fighting, sacrifice a 2nd exotic in the name of the sun. Randal the vandal will come out of the star gate while riding on Hank the shank and will begin to wreck Crota and Atheon. Once they go down you and your fireteam will have to defeat Randal. Once the epic battle is over Randal will drop the weapon of your choice from the raid.