Firstly here is some basic lore stuff you need to know 1.- There are variants of each agents from 2 alternate earths 2.- The agents defusing on most maps except pearl are the alpha agents (Our earth) and the agents attacking on all maps except pearl are the omega agents 3.- Kay/o comes from another alternate universe where there was a devastating war for radianite, in this alternate universe sage is a stone cold killer 4.- Omen died during the first light for reasons unknown and sage failed to revive him, leaving him to be in his current state, however omen does not hold a grudge against sage

Essentially for reasons I will not go into in this post alpha astra and harbor are looking for an ancient city, opened with the artifacts they currently have, however upon finding out the location of the city they are dismayed to find out the city is “gone” so they travel to omega earth where they try and see if the city is still standing there (which it is) however omega fade is close on their trail (Somehow I really dunno how she knew about the city in the first place) and also obtains the location of the city dispatching alpha agents to the city before alpha harbor and fade arrive in order to ambush them, which is what we see when astra and harbor arrive at the inside of the city.

What about sage and omen? Omen decided to go help Sage as he noticed she was struggling handling the bots alone and as for Sage she was practicing her gun skills because in omega earth she is no healer, and we can deduct from dialogue from kay/o that it is actually incredibly strange for alpha sage to just be a healer and not a cold blooded killer as in kay/os universe and in omega earth sage seems to be a regular agent like everyone else who goes out and actually fights instead of just staying with brim.

If I missed anything please do leave a comment and ill try to answer