When they reach the forest of anomalies, Marcus suddenly glitches and remembers that he has gone through this a million times before and he will forget this again, just like before. They agree to help him and they begin the invasion the next day.
Not wanting to waste his soldiers, Marcus ordered the trio to join him in the 'holy war' with the Heralds.
He then commands one of his soldiers to arrest them, but the soldier gets defeated by the player instead. Marcus was encouraging his army to attack the Dome when the player, June, and Itu suddenly appear before him and his army. It's evil, and you mustn't fool around with evil. He almost succeeds, before Bolo teleports him to the timeless dimension, trapping him in an endless time cycle. Marcus led an army that aimed to destroy the Heralds, the Dome, and the Sphere.
1.5 Chapter VII, Part II: Behold the Future.