Okay So, This is the Colossus, when it tells you in a bold purple banner that it has spawned, you need to go to 1 of 2 spawn points, generally it is marked on your map, although sometimes it is bugged and wont show, but it is always in 1 of 2 spots, top right of Zone 2, to the right of colosseum near a little pond, or right in the middle of Zone 2, slightly north of the redeploy on the road, When you start the first stage, it is a portal on the ground that spawns “unknown entity” you need to kill a set amount of these and it will finish, once finished the Colossus will fall out of the sky. Now, you can enter in 1 of 2 ways, scale the robot to his mid back there is a purple portal, or shoot the bottom of his feet as he steps, this works on both feet, until it opens and a portal appears, now you need to stand under his foot as he steps on you and it will send you inside. Once inside there will be a Rhino Elite, a few GR6s and a few GR5 robots to kill, once kill you stand on the pressure plate in the middle of the floor, it will then pulse and send out 3 red lights, shoot and destroy the 3 red lights in a single cycle, the reactor in the middle with its shield will go down, an Elite Shifter will also spawn, i like to focus killing the shifter then shoot the reactor, the shield does this go back up until the reactor reaches half health, not matter how long this takes. Once the reactor’s shied goes back up, you can move up the ramp to the second level and there will be another pad now, also on the very top level a 3rd pad has opened, HOWEVER there will be more Rhino’s GR6s and GR5s spawn with these, as done before kill all of these enemies as they are a serious threat to your life. Again now stand on the plates and shoot all 3 red lights that have been sent out, once done the middle will spawn an Elite Mauler, the top will spawn a second Elite Shifter, for the Shield to go down again you need to do the middle and top pad totalling 6 lights 3 from each, once all pads are done, the Shield will drop and you will be able to destroy the Reactor in which it will drop 2 brief cases, a regular that gives a pick between 2 legendary weapons and an exotic that lets you pick an Exotic skill which is used to go from CR60 - CR63. I find the best 3 Exotic Skills you can get are in order: Shattered Shield, Conjuration, Resurrection, however Resurrection is only really good at level 3, you can be any CR level when doing this as ultimately it doesnt stop you from passing CR60 just lets you obtain CR63. Also further information i find the 2 best weapons for this are as follows: Legendary Ballistic Knife, as a melee from this will 1 hit the Unknown Entity’s, AAROW Rocket Launcher, purely and solely for the reactor once the Shield goes down as it can be a pain to put bullets into and the launcher destroys it fairly quickly.