A few things to note when creating an Invasion server:

* Set your world type as "BIOMESOP" or the world will not generate properly.

* When setting up HQM teams, players need to log off and back on 1 time due to a small sync issue. This will allow them to interact with quests correctly.

* If you're playing Coop, make sure to note mobs get more difficulty as time progresses. Make sure to shut the server down so you don't log back into insanely difficult enemies.

* If you're playing a larger multiplayer server, the following mods should have their spawn days/rates adjusted: Drones, LaserCreeperRiderDinosFromSpace, and Raiders. You can set their spawn days back to allow players more time. The Raiders mod has a difficulty rate: 

    # This is the Raid difficulty. Each set amount of days the mobs get harder(Raid Difficulty increases +1). Each x amount of days harder mobs have more of a chance to spawn its cumulative [range: 1 ~ 100, default: 5]
    I:"Raid Day Difficulty Progression"=8
    S:"Raid Difficulty Day Progression"=8

Set these numbers higher so they do not get difficult as quickly, so instead of getting more difficult every 8 days, they can be set to every 30 days, etc.

If you plan on having a server running for multiple people over the course of a long time, it's probably best to set these times in the hundreds.