I could see a world boss event on Venus with a mini-boss in front of the Vault entrance, then you continue on past it, through Campus 9, to the Gatelord area for one encounter with the boss, he escapes through the portal behind him and if you aren't right with him to go through it within 5-10 seconds, you have to backtrack through the area that you capture Skolas in and open a gate there that will take you to the correct timeline and place. If a fire team member was able to go through, they could assist in opening the correct portal from the other side, or keep the Gatelord from regenerating his health by disrupting the flow of time around him (alternate portals that you would have to close by standing on their activation circles) or continuing to deal damage to him (not as effective as sealing the gates feeding him). There could also be small Nexus Minds helping to protect/feed him that you could take out to slow the regen. Once the whole fire team/s is/are through to the final area, two Cyclops pop up and start firing on the team/s and the Gatelord begins fighting, with a shield generated by the Cyclops and a sealed Nexus Mind behind the gate the team came through. (Trapping the team/s in the area with the Gatelord.) The team wipes out the Cyclops and the Nexus Mind, (Gatelord taking minimal damage each time as the shield turns on him and freezes him for the fire team to deal some damage, on top of what the shield does) then if he hasn't been finished off already by the time you have killed all three he escapes into time again, ending the encounter. He won't be immune during the time he is heading to the large portal off to the side, so he can be killed during this time, he is just trying to escape the trap he set for you and your fire team/s. He will still react as per usual, maybe a bit more defensive.