Operation D: Adamantine Shield

Operation D: Adamantine Shield is the fourth operation of Halo: Spartan Strike. This operation is an in-universe simulation of the Battle of New Phoenix, following a Spartan Headhunter's attempt to close a slipspace portal in the city.

Missions

 * The Way Home
 * Serve and Protect
 * We Need to Talk
 * Reverse Course
 * The Lion's Den
 * End of the Line

Transcript
{Cutscene}

''As the Spartan escaped with the Conduit, he received an emergency distress call from a top secret ONI base in New Phoenix. Researchers there were studying a mysterious Forerunner artifact. When the Covenant used the Conduit at the Altar, they activated portals all over the galaxy. One of those portals was in New Phoenix, and... Well, you can guess what came next.''

What's more, the only way to close the portal was to bring the Conduit to the base—and use it to deactivate the Forerunner device.

''The Spartan raced towards Earth... But the Promethean invasion had already begun.''

{Closing cutscene}

''Outstanding performance in our simulation, Spartan! There's no telling how many lives would have been lost if the Promethean onslaught had continued.''

''Instead, we closed the portal and stopped them in their tracks. As for the Conduit itself? It jumped into slipspace before we could grab it. Official press reports referred to a "slipspace drive coil accident." Had people learned the truth, the resulting panic could have destabilized the Unified Earth Government at a crucial time.''

''Luckily for us, that didn't happen. But the Conduit isn't the only Forerunner artifact out there. The lost treasures of Forerunner civilization offer us great opportunity, and even greater peril.''

{All missions gold}

''Greetings Spartan! Congratulations on your exceptional performance in our simulation! I've got a classified update for you, if you're into that sorta thing...''

''Since the events in New Phoenix, ONI has been working day and night to track down the missing Conduit. We suspect it broadcast an activation signal to Forerunner portals across the galaxy.''

''Portals we don't even know about. And while some of those portals may be dormant, others are still very much active.''

We need a special team of Spartans to seek out these portals, shut 'em down, and stop the spread of the Promethean threat.