On their way out of Under Port, the trio received a communication from Keira. "Thanks for getting the artifacts guys. It's strange, though. The Time Map had a bunch of old coordinates in it. Come see me at the stadium."
"...we'll be right there," Jak replied quietly.
"...is everything alright Jak?" Keira asked worriedly.
"We...we lost Sig."
"Oh...Jak..."
Silence reigned after that, and the communications were cut. It didn't take long after that for the trio to reach the stadium, seeing a much larger and better equipped contingent of Crimson Guard patrolling the streets to take down the invading Metalheads. With Praxus working for them instead of against them, more resources could be directed towards beefing up anti-Metalhead defenses.
When they reached the Stadium, they saw Keira waiting for them outside along with the completed Rift Rider. When they approached, she quickly pulled all three of them into a hug. Nothing was said. Jak, Shining, and Keira all knew who Sig was as far as their long term goals, and losing him made a great many things a lot more difficult in the future. While Daxter wasn't completely in the loop, he decided not to stick his nose in just yet.
After a time, Keira raised an unrelated topic to clear the air. "The Rift Rider's finished, but Father says the Ring is somewhere in the Metalhead nest."
"Any plans on how to get it there?" Daxter asked curiously.
"Look!" Burta proclaimed as he popped out from behind the Rift Rider, pointing to a balloon carried wooden platform. "Bruta just knew friends would need lift if Metalheads attack!"
"Nice one, Bruta!" Daxter praised, fist bumping the Lurker.
As the two Samoses used their Eco to lift the Rift Rider onto the Lurker Balloon, Jak, Shining, and Daxter worked to take down attacking Metalheads. Jak and Shining utilized their guns and Eco Blades, while Daxter took advantage of his newly discovered abilities by grabbing a good sized - for him - blunt instrument and smashing. With the three of them working together, they were able to keep up a full circle of protection, and the fact that it was only the smaller scorpion like Metalheads attacking made the whole endeavor go much faster.
Once the Rift Rider was loaded onto the balloon, Keira and both Samoses went with Bruta to take the aerial route to the Nest. As they left the stadium, they got a message from Praxus. "Jak, I've managed to recover the Precursor Stone. It turns out no one actually stole it. Mar's Crocodog swallowed it. I've got it now. Meet me at the Construction Site, where Metalhead activity is at its lowest, so you can take it to Mar's gun to power it."
Knowing that it was time to move fast, the trio made their way rapidly to the Site.
Once at the site, Jak and his friends rushed forward to meet Praxus and his men, only for Kor to drop in out of nowhere. "Kor?" Jak shouted out. "What are you doing here?"
"I'm sure you know," Kor replied, his voice wicked. "Deep down in your darkest nightmares!" As he said the last word, his face warped, his teeth becoming razor sharp. He then let out a high pitched whimper as Shining shoved an Eco Blade into his crotch. "I'm trying to do my dramatic reveal here," Kor complained.
"Yeah, you're the Metalhead leader disguised as a human," Shining replied. "Saw it coming. We've been keeping you in the dark on certain details for some time just in case." He pulled the blade out, only to shove it in again.
"...you know that's not damaging my true form at all," Kor indicated petulantly.
"Are you in pain from it?" Jak asked curiously as Shining drove his other blade into Kor's belly.
"...excruciating," Kor whimpered.
"Then I'd say it's a worthwhile endeavor," Praxus grunted, driving his Eco Blade into Kor's skull.
With a deep growl, Kor blasted them all away as his body erupted. "ENOUGH!" he snarled as he expanded. Four insectoid wings erupted from his back, six legs burst from his stomach, his head warped into a visage of death, and his spine ripped free to extend into a massive scorpion sting as he expanded to ten times the size of those around him, the human form torn asunder. "You see," he explained, "without the shield wall disrupting my power inside the city, I have my full potential! Now where is the Precursor Stone?"
"Daxter has it," Jak replied bluntly. "He's already on the way to use it to breach the Nest."
With an angry roar, Kor lunged into the sky.
"Nice bluff," Daxter whimpered from the small of Jak's back.
"Here," Praxus said quickly, handing over the Precursor Stone. "You'd best hurry."
Making their way out the Wasteland, the trio followed the map Praxus had provided them to Mar's ancient weapon, a massive gun designed to shatter the Nest Barrier to allow a more direct incursion. Numerous highly nimble Metalheads leapt about as they tried to slow the trio's progress, but they moved in hard to get past them. The only real obstacle they encountered was a massive Metalhead guarding a bottleneck with a rapid fire Eco weapon, but they were able to get past it by waiting for the weapon to overheat before lunging in to blast away.
The 'gun' itself was massive, as big as a building and mounted with the turret pointed at a large mountain. The trio rode the elevator to the ammo chamber, and Jak carefully placed the Stone in the proper slot. Immense amounts of Eco poured out of the Stone, filling the gun before it unleashed it all in a massive blast, ripping the mountain open and leaving a clear path into the Metalhead Nest. Jak pocketed the Stone as the trio made their way through the hole.
The path into the Nest itself crossed over lakes of Dark Eco, which released purple gas into the air constantly, filling the path with a dark fog. The Metalheads were much stronger inside the nest, and actively worked to take down the trio. However, much as Jak had predicted, they didn't actually know how to handle small groups or single targets all that well, and the weapons fire they were able to bring to bear mowed down the defending force. What they could see clearly of the Nest after that rather closely resembled the inside of a beehive or anthill, but on a much larger scale.
Eventually, the trio reached the central chamber, where Kor waited. "Finally...you've decided to join us," he whispered, moving his tail to reveal Mar and Ar-Mar, trapped in a Dark Eco sphere only just held at bay by Ar-Mar's shield. "And you brought the Precursor Stone. Good. The boy will now play his final part-"
"Since we already know most of the crazy time shenanigans going on," Daxter interrupted, gesturing to the Rift Ring nearby, "can we skip all the exposition, get the Cliff Notes, and just fight already?"
Kor frowned. "You know, you're taking all the fun out of this," he grumbled.
"Yeah...don't care," Jak countered. "By the way, I'm guessing you expect you can feed on the Eco inside this stone?"
"It's not just Eco!" Kor snapped. "It is the last Precursor life form! And it will only open to one with the pure Eco gift of Mar, undiluted by Dark Eco...one of the same bloodline as the Precursor inside!"
"Then it's a good thing there's two of me here," Jak commented dryly. While he wondered why the Stone hadn't opened when he'd handed it to Mar back in Mar's tomb, he guessed it hadn't been ready to open for whatever reason. So he had a new plan now: smash Kor, give Mar the Stone, watch the fireworks.
Kor, as it turned out, was disappointingly easy to take down. His wings hooked him to the roof of the Nest, making him a sitting target. Jak focused on shooting him while Shining and Daxter took out the Metalheads Kor spat out in eggs to attack them. He occasionally fired off a blast of Dark Eco at the group, but he telegraphed the attack too much to hit.
"It seems I was right," Jak muttered. "Against armies, you're all designed to consume everything...but a well armed lone warrior - or a small group - can easily take you down."
With an enraged bellow, Kor disconnected himself from the roof of the Nest to charge the group...only for the trio to scatter. Jak and Shining drew attention while Daxter quietly crawled under Kor before leaping onto the massive creature. His light weight went unnoticed as he crawled up the carapace.
Before long, Kor was able to corner Jak. "This ends now!" he bellowed.
Jak grinned widely. "You're right about that," he agreed, hurling his Eco Blade upwards.
Daxter leapt up, catching hold of the blade and bringing it slamming down onto Kor's forehead crystal, Light Eco surging along the blade. The crystal cracked and the beast began to stagger, only to stumble into the Rift Gate and explode.