Ancient Egypt…

"What's going on here? Where am I?" Sabertooth said as he found himself strapped into a containment pod.

"Cease your struggles. Those restraints are composed of adamantium, a metal which even your elephantine strength cannot break." Beast said as his eyes had black eye shadow around them and his fur color was a bit lighter as Quicksilver and Polaris were seen behind him in the same containment pods as Sabertooth, except they were unconscious.

"I'm gonna paint this whole room with your blood!" Sabertooth roared.

"Though limited, your vocabulary is certainly colorful." Beast chucked deviously.

"You can't do this! You're an X-Man! You're an X-Man!" Sabertooth yelled.

"I...am...was...an X-Man." Beast struggled to say.

"Having second thoughts, Beast?" Apocalypse asked as he entered the room.

"No, no. Not at all." Beast said as Sabertooth's pod powered on as he too fell unconscious.

"What of the Nexus? How soon until it is functional?" Apocalypse asked as he soon stood before all four of the Harmonic Mutants containment pods.

"Synching four genomes is no small feat. The energy generated by infusing these four mutant genes is far greater than had been guessed - Perhaps even more than you could cope with." Beast said.

"You underestimate me, Beast. Once I wield the power of the Four, I will be invincible. None will stand in my way and I will see to it the X-Men, Brotherhood, Spirit Force, and Reformed Society are utterly annihilated! HAHAHAHAHAHAHAHA!" Apocalypse laughed.

The group soon reconvened with Professor Xavier in a part of a Pyramid.

"Thanks to your efforts, the remnants of Apocalypse's force are falling quickly. The authorities expect to regain total control of New York City in a matter of hours." Professor Xavier said.

"So we're in Ancient Egypt now." Ace said.

"I find it quite ironic to be honest." Belladonna said.

"How so?" Al asked.

"Well, legends say that Egyptians have worshipped cats since ancient times." Cheetah said.

"Oh yeah! And we've got four feline-trait girls here." Al said.

"Well not exactly a feline trait for me since I have a tiger spirit." Razmi said.

"In our opinion, quite fitting for a final battle in this place, wouldn't you say?" Cheetah asked.

"Yeah, defeating Apocalypse in the very place he was born." Simon said.

"Yes. But first we must locate Beast - He would have information on the machine Apocalypse has labored so hard to build. That device causes me the greatest amount of concern. Beast is our only hope of discovering what Apocalypse has planned." Professor Xavier said.

"Chances are Mr. Sinister will be with Beast too." Lei said.

"He's the one holding Beast under mind control. We'll have to defeat Sinister to set him free." Cheetah said.

"Two birds with one stone. Time for some spelunking." Al said.

The group began their trek into the Pyramid as they began fighting off large Scarabs and Anubites before they soon reached a room where Beast and Mr. Sinister were waiting for them.

"Hello, my dear 'friends'. You have no idea how difficult it was not to laugh every time I spoke to you. There I was 'the traitor' right under your noses." Beast said.

"Henry, please, think about what you're doing. This isn't like you at all." Storm said.

"Storm, you're wasting your time. Beast is one of us now, he's right where he belongs." Mr. Sinister said.

"Sinister, I've never enjoyed seeing someone in pain. But in your case I might make an exception. Give us back Beast...or else!" Storm said as lightning surged from her eyes.

"Or else what, my dear lady? Are you going to get physical? I hardly think you have the power to stop me." Mr. Sinister said.

"You'll be surprised what we're capable of in the right circumstance." Cheetah said.

"Hahaha! In that case, show me then!" Mr. Sinister said.

"With our most sincere pleasure." Cheetah said.

"Once Mr. Sinister is down, knock some sense into Beast!" Harpuia said.

"Aiming Device!" Ace called, aiming a laser at Sinister with Breidablik before firing. "Air Slash!" he called, jumping into the air before slamming Celestial Twilight onto the ground and launching a shockwave towards Sinister.

"Lend me your strength, Zacian… Moonblast!" Zamazenta said as an orb of light was fired at Sinister.

"Let me lend a hand." Zenji said. "O mad and greedy waters, rise up and storm the very heavens… Tidal Wave!" he casted as a large mass of water appeared and washes over Sinister.

"Let it be decided here and now." Atro said. "Ye must desire respite from thy empty existence, thou shalt have it! Celestial Star!" he chanted as multiple feathers of light dispersed and began swirling around forming orbs of light as they launched down beams of light onto Sinister.

"You were lucky this time. But it won't happen again." Mr. Sinister said before falling.

"Beast! Are you okay?" Cheetah asked.

"Yes… I believe so. Sinister's deadly cocktails have finally worn off." Beast said. "And aside from being pummeled by the likes of you, yes, I'm fine now."

"Can you tell us anything about Apocalypse's experiment?" Mari asked.

"He had me build a machine that would harness the powers of four mutants with Harmonic DNA. The machine then transfers that power to him. Once the machine is fully activated, Apocalypse will be nearly invulnerable." Beast said. "He's further inside this Pyramid, behind a great seal guarded by the Living Monolith."

"It all makes sense now… Quicksilver, Polaris, Emma Frost, Sabertooth… They weren't kidnapped for just any old reason. Their powers combined would make him invincible." Cheetah said.

"Hmm." Tsuki said, closing her eyes in thought. "What if we used it against him?"

"You may be quite right. Let us proceed. We must stop him while we still can." Cheetah said.

"Good luck to you my friends, I shall await your safe return." Beast said before heading back to camp.