From what I know, warlocks use their super when he is backed against the edge of the map. Warlocks use their super right in front of him and he tries to get away and walks back off the map and dies. Kind of a bad explanation, but you can probably find a video about it on YouTube.

You use between 1 or 2 warlocks depending on how confident / good the main "leadlock" is at kiting Atheon into a good spot for pushing him over the edge.

you run to a certain pillar at the begining of the boss encounter as he is still phasing in/forming and using aggro mechanics of the game make him side step round the pillar you are using as cover, you are aiming to time it right so he is closest to the edge but against the pillar when he opens the timewarp/timeframe.

as the team killing oracles comes back the warlocks spam the super with damage over time enabled and vortex grenades if wished near his feet in such a way to make him want to back up off the edge of the map as supers refresh at a very quick state as you see the "the guardians make their own fate" or something like that message.

there are plenty of videos online about it and it is now fairly common practice as a end boss tactic and no doubt going to result in bungie patching his mechanics and way his AI respondes to certain things.