YMMV / Chapter Master

• Demonic Spiders: Chaos Daemons on Daemon Worlds. Taken straight with Necrons if you fail to blow up a still dormant Tomb World.
  • Chaos Fleets. Especially if they warped out of nowhere and go straight for the nearest strategically vital planet n the sector...or your homeworld if you have one.
  • Tyranid Fleets. Just Tyranid Fleets.
    • With the recent patches Necrons gain their own fleets now.
  • An Ork Waaaagh! arriving into the sector is nothing to scoff at either. While they are not as bad as the Tyranids, they still start out by rushing an entire cluster of stars with tens of battleships.
• Game-Breaker: Some combination of traits and wargear can go into this territory when you arm a highly experienced marine with them.
  • Taking the Melee Enthusiasts, Bolter Drill, Slow and Purposeful, and finally the Ambushers traits makes Space Marines truly terrifying when raiding.
    • Another one is to take the Lightning Warriors trait over either the Slow and Purposeful or Ambushers trait. On one hand you get a boost to damage at the price of having your resistance lowered. On the other hand your marines will be dealing colossal damage.
      • The Terminator Armor + Iron Halo + Storm Shield/Storm Bolter + Thunder Hammer combo turns your marine into a Nigh-Invulnerable Mighty Glacier. Combined with the first set of above traits makes these warriors a force to be reckoned.
        • Artificer Armor + Iron Halo + Jump Pack/Bike + Storm Shield/Plasma Pistol + Thunder Hammer is also a viably deadly combo.
          • Certain Artefacts you get your hand on are greatly more powerful than normal weapons and wargear you use. Even more so with Daemonic Artefacts.