Awakening Tomb World

I have a one off idea for a small contingent of Death Watch Marines responding to a summons to act as first responders to an Awakening Necrons Tomb World that was recently discovered.

I plan on creating a storyline with the one offs with different characters, this being chapter 2.

For enemy encounters (Set at Tier 3), I'm expecting to throw a lot of Canoptek and basic Necrons (Warriors and Immortals), at the players.

On top of that, I'm also planning on there being a sleeping Phaeron on the planet, so that would also increase the potential threats on the planet.

I was wondering if anyone had any ideas for basic objectives for a Deathwatch team to complete in order to buy time for a proper military force to be raised to respond to the threat. And if there were any sources out there to help educate me on awakening Tomb worlds.