Travel back to your ship and climb aboard. Select the Pirate Seed location to find yourself arriving in a very familiar environment by now. This is the final active Seed - destroy this one to seriously cramp Dark Samus' plans for galactic domination. Be sure to save your game here before venturing further in. This first squishy and pulsating chamber bears almost identical decor to the ones found within the other Leviathans, so you should know the lay of land by now.
Swarms of Scritters scurry about down on the chamber floor below, be sure to clear them all out for one last chance at the Exterminator Friend Voucher if you hadn't cleared the critters out of one of the previous Leviathan Seeds. Now let's find out who's guarding this rock. Leap across the floating squishy platforms and employ the Screw Attack to reach the exit on the far side.
Step through the door to find the Core's connecting corridor blocked by a compulsory guard. This weird Phazon growth looks something like a spiny tentacle, one which oddly doesn't lash out as you approach. Scan the oddity to learn that its thick durable hide conceals a weakness beneath. So simply fire up your X-Ray Visor to reveal a deep inner Phazon core. Lock onto the glowing red center and pump a single Nova Beam shot into it to blow the tentacle apart.
Step down the twisting organic tunnel and clear out the second tentacle barring your path. Reach the exit down the far end and step on through to discover the Leviathan's core chamber where a truly heated battle awaits. You've faced the worst the Pirates could throw at you - time for the ultimate test. Climb down to the base of the seemingly deserted chamber and step towards the center. Watch as Samus cautiously peers around, waiting for something to strike. And strike it sure does.
None other than Ridley himself swoops down through a pulsating wall, madder than ever thanks to his defeat back in Generator C on Norion. Upon landing and exchanging a quick melee with Samus, you'll face the guardian of the Pirate Homeworld Leviathan Seed. Appropriately named Omega Ridley, this final Phazon-powered incarnation of your nemesis won't be a pushover, so refer to the bosses guide for some handy tips to rack that Ridley-kill count ever higher.
With this ultimate form of Ridley suffering a humiliating defeat, Samus is in for a nasty reward. Proximity to the Phazon-powered explosion ripping Ridley's body apart fills Samus with her latest dose of Phazon corruption - surely the worst one yet. With the growths inside her body growing dangerously large, the poor hunter is now an almost spitting-image of Dark Samus - most of her suit now glows a severe blue (but with red tones from her helmet and the green glow of the Nova Beam she's quite a colourful sight).
All hope is not lost however. Resting where Ridley once stood is your final suit upgrade - the Hyper Grapple! This handy tool grants Samus' Hypermode its very own Grapple Voltage function, something you'll definitely find coming in handy soon. Secure this final upgrade to find your item percentage strike home at 100%! (if you've been following this guide, otherwise you'll still need to backtrack and find any leftover items)
The game informs you that yet another secret ending has been unlocked, and the simple task of completing the game is all you need to do to watch it. Just like the previous two Leviathan Seeds, you'll now find yourself locked in a (safe) permanent state of Hypermode as a pair of thin lengthy Phazon growths droop down from the gross ceiling.
Time to put the Hyper Grapple to good use. Lock onto the C-icon on each tentacle and deploy the Grapple Lasso. Hold forward to deliver overloading Phazon energy into the organic masses, blowing them apart quickly. With both tentacles dispersed, a deadly wash of Phazon energy erupts from their stumps and strikes the Leviathan Core's bloated sac.
Emerging from its foul hole, the Leviathan Core should know what to expect by now. Hovering into the air with Phazon energy coursing over Samus' suit, you'll see the warning message to simply press A to release Phazon energy into the core. Do so and watch as the final Leviathan Seed's core can't take the barrage, landing in a heap on the floor before erupting in a squelchy mess.
That's it, you've done it! But once again not without serious cost. Samus returns to her gunship and departs the Pirate Homeworld, heading for orbit as the Leviathan rips itself apart. Aurora 242 promptly chimes in over the radio with her congratulations - this is certainly no easy feat we've achieved today (I say it always, but especially on Hypermode difficulty).
Phazon corruption has now been halted, but one final task remains - the utter destruction of Phaaze and the end of all Phazon. But how to get there? Your good buddy Aurora 217 has pinpointed the location of all the Leviathan's origin - no doubt the sentient planet Phaaze.
The Pirates have been completely routed and no longer pose a threat to the Federation here on their homeworld, but Phaaze is far too distant from local space to simply take a trip through hyperspace. But yet again, the Pirate's sloppiness is their undoing.
Amazingly, the Pirates have left behind one remaining Leviathan battleship holding orbit over their Homeworld. Completely inactive and without protection, this floating Phazon mass is the Federation's key to opening a wormhole to its origin.
A warp device hidden on the planet's surface has also been discovered - that's your ticket to board the Leviathan and take command of the hapless vessel. Revealing the warp device a short distance from the Command Station, we'll be heading down once again to the Pirate's main facility.
But before selecting the Command Center, be sure to conduct a biohazard scan to learn that Samus' body is now 75% Phazon corrupted. That certainly isn't good news.
To top it off, switch on your Scan Visor and look up out the window. The reflection of Samus' face is now dominated by huge blue Phazon veins, while the whites of her eyes have now become jet-black and her left eye's pupil replaced with a glowing blue hue. Certainly not her best look. We'd better do something about this - she can't survive another dose of Phazon corruption.
Touch down at the Command Center and step off your ship. Move forward to find company - from now on every landing site here on the Pirate Homeworld is guarded by a pair of Federation PED Marines - looks like they've got everything under control here now. Feel free to chat to both before moving onward. Travel up to the Command Station chamber from here and step towards the grotesque Phazon growth still inhabiting one corner.
Remember how you couldn't harm this mass before? Not this time. Enter Hypermode to see a shiny C-icon appear over the growth's blue eye. Simply attach the Grapple Lasso and use the Hyper Grapple to deliver an overloading blast of Phazon energy into the mass, obliterating it completely. Step through the uncovered door to locate a hidden transit station, unused during all the recent chaos.
Summon the train as per normal and step aboard. Activate the control terminal to find yourself whisked away to a transit station right next door to the Leviathan teleport chamber. Exit the transit station to discover the Leviathan Access Portal inside a cylindrical chamber.
Completely protected by an active energy shield, it looks like there's a nearby power terminal ready to be drained. Climb up to the energy shield and take a look at your surroundings. See the damaged grate on the wall? Blow through it with a bomb and climb down a narrow maintenance tunnel.
Down below you'll discover the energy shield's power source. Simply attach the Grapple Lasso and drain the device of power to instantly power down the pair of energy shields. Climb up to the portal to find a huge glowing hologram representing the Leviathan rotating ominously. Scan the hologram and the portal's platform to learn that this device indeed does link to the orbiting Leviathan. So take a deep breath and step atop the platform.