Your primary job here is retrieve the summer icon from the caverns beneath the Southwestern part of the citadel, in order to prevent its acquisition by the likes of Fractilion during this unfortunate invasion. Quite possibly, he poses more of a threat than the insectoids. This incident was the perfect cover for him to steal various and sundry valuable objects.
From what I've heard, the only way to get down there is to jump into the fungus pit. Certainly disgusting, but you should come out unscathed, and I doubt many of these nasty creatures have made it down there. The tricky part is going to be inserting the icon into its rightful receptacle, which is pictured here. It's in the sewer. Undoubtedly, you'll be covered in more than one kind of fungus before this is over. There are at least two ways into the sewer. You may have already found the locked entrance to Sewer Node A, you may be better off looking for Sewer Node B. The time I've spent here is minimal, so I'm not sure where it is, but I remember Fractilion saying it had no door. There's also an important switch located there.
Once the icon has been inserted, you'll be able to smash the Icon Powered Xontrol Access Panel, pictured here. You'll likely have to hit it with something pretty hard. The emergency shutters should auto-close if you've done it right. If you manage to flip the switch at Sewer Node B and smash the Icon Power Xontrol Access Panel, you should be able to access both Xontrol Rooms to the East. Directives from WORLD VOICE state to destroy any visible wiring in both rooms, terminating the mining and fuel synthesis operations in this sector. If the fueling heart fills with pink liquid, you'll know you've succeeded. After you're done with all that, find your way upstairs to the enchanted lounge. If all goes well, I'll have figured a way to get you out of here.
As a side note, you should encounter this Armory Failsafe switch somewhere on the way to finding the icon in the Southwest. The Armory, as you might guess, contains a profound quantity of guns and ammunition. Unfortunately, it's located in the fueling heart, which will be filled with boiling liquid by the time you're done. If you want to access the armory, you'll have to do it before visiting the Xontrol Rooms.
This area of the citadel is much older than the rest; it's been here longer than even the most ancient of us have been alive, and there are only rumors as to who its creators may have been. There's a tunnel that leads out through the back of this lounge to the so-called claw outpost, positioned on a rather jagged cliff. It hasn't been used for much of anything in years, and when you're done here, you can use the transport capabilities of its terminal for a covert escape from the area. The tunnel won't be open to you unless you manage to light both of the monkey's eyes, which likely won't be possible until the icon is placed and the rest of your work here is done. You can blame the ancient creators of this place for the esoteric animal symbolism.
Such cautionary tactics as practiced by the WORLD VOICE would have stopped the entire progression of modern science in its tracks long ago, and are, in the eyes of a pragmatic being such as myself, synonymous with waste and lost potential, for what good is mining ore if the true power of the material is made to remain dormant forever within it!? It's no wonder that among such company I serve as my own mentor. Of course, I'm a fool to expect sympathy from you. Go on, carelessly smash 3000 years of ingenuity with your thuggish caveman hands.