Now it's time for an upgrade that will open a lot more of the game to explore. The trade off though is there is a rather nasty boss guarding it and there's a tough battle to fight.
Go to the door across the courtyard from the Save Station and scan it to learn that it needs power just like the one in the Research Core. Scan the metal arch above the door to learn that there is a power conduit here but it's blocked by a Cordite statue. Cordite means you need a Super Missile so shoot one at the statue. Then switch to Thermal and shoot the Wave Beam at the power conduit to power up the door. Now you can go through. (If you already know where the power conduit is then you don't really need the Thermal Visor to get through this door, which means that you can get to the next boss without it. It's a bit of a sequence break but since you need the visor to defeat the boss, or at least it will be very difficult to win without it, it isn't a good idea.)
There are Bombus patrolling this passage.
North Quarantine Tunnel
This is a long Morph Ball tunnel with Bombus about midway. There is nothing you can do to get rid of the Bombus so either time your way past them or use Boost Ball to take your chances and power your way through.
The size and shape of this large dome suggest that this is where the boss battle will take place, but there's nothing here but a pile of boulders. Drop down to ground level and a cutscene starts. First a small rock start to move by itself, then the entire pile of boulders organizes itself into a giant made of rock. This is the main boss for Phendrana and the hardest boss in the game so far.
Thardus leaves behind some Ultra Energy so you can recover a bit, and the Spider Ball. This allows you to follow the Spider Ball track that's to be found in many locations in the game. Start by scanning the track leading up to the ledge where you came in. You can use this track to get to the ledge exit that way, and this might be a good idea so you can get back to the previous Save Station to save your progress, but come back here when you're done. The next time you enter this room there will be a Sheegoth here to keep you from getting bored.
Expansions (Phendrana Drifts)
Time to explore the parts of the game that the Spider Ball opens up to you and collect some well earned expansions.
Go up the rightmost Spider Ball track to the ceiling, and follow it to the left as far as you can. Let go to drop onto a new ledge and go through the door there.
South Quarantine Tunnel
This is nearly identical to the North Quarantine Tunnel.
Transport Magmoor Caverns South
There is a Spider Ball track here but it's a dead end for the time being. Take the lift.
Expansions (Magmoor Caverns)
Transport to Phendrana Drifts South
This is where the lift takes you; there is a save station behind you, so turn around use a missle to unlock the door then go through and use this opportunity to refill your energy and save your game.
Transport Tunnel C
Time your way through the jets of flame coming from the ceiling.
This is a large cavern with Pirate technology scattered around. Flying Pirates attack when you enter.
Scan the machine under the ledge where you came in to learn that it needs power from three conduits. These are located next to the three colored doors located on three sides of the room. Find them using Thermal vision and activate them with the Wave Beam.
Now the machine is on and it cools the lava in one of the passages under the floor. It also opens a gate so you can get through. Switch to Morph Ball mode, drop into the hole in front of the machine, and follow the passage through the gate into a side room. There are Triclops in the passage to make it a bit more interesting. Scan the panel in the side room to cool the lava in another passage and open the another gate. In this case there is a time limit, so quickly get to the opposite gate (colored green). Scan the panel here to do third passage and gate, this time go to the right (purple) gate. This side room has an Energy Tank and the timer automatically stops when you collect it.
There are two exits here but one is a dead end now. Go through the door between the green and purple gates.
South Core Tunnel
There is a pool of lava here with a creature floating in it. It's called a Puddle Spore and it's actually helpful though not by choice. Wait until it opens its mouth, then shoot it. There's no harm done to it but it will flip over creating a stepping stone for you to get across the lave.
There are some platforms here but you can't reach them yet, so just use the Puddle Spores to get across the room.
North Core Tunnel
Use a Missile to drop a stalactite into the lava and use it as a stepping stone.
In the first section, drop a stalactite into the lava as a stepping stone to some ledges on the right. Then drop a second stalactite to make a stepping stone to the far side. Use Morph Ball to roll under the jets of fire to the next section.
Drop another stalactite to get across the second pool of lava, then time your way past the jets of fire to reach the exit.
Twin Fires Tunnel
Roll into the hole at the side of the passage, then use Spider Ball to follow the track up to the ceiling, across the room, and back down to the ground again.
Transport to Tallon Overworld West
This lift takes you back to Tallon Overworld via the Root Cave. There's still more to do in Phendrana at the moment though so continue through the other exit.
Transport Tunnel B
Switch to Morph Ball and follow the grove in the wall on the right. This turns into a kind of Morph Ball rail which you can follow to the other end of the room. A Magmoor will attack on the way, and this is pretty much unavoidable going this direction, but if you're quick you won't take much damage.
Now you're back in Fiery Shores which was covered earlier just after getting the Varia Suit. Continue on to return to Phendrana Drifts. This was a round about route to get back near where you started, but there was an Energy Tank collected, always worth while, and lots of the map filled in.
Expansions (Phendrana Drifts, cont.)
Get to the portico on the far ledges as before. Find the statue to the left of the door; if you scan it says it's made of Cordite, so fire a Super Missile at it. There is a symbol underneath and when you scan it a small gate opens on the left. Switch to Morph Ball and follow the Spider Ball track up to the top of a tower and collect a Missile Expansion.
Ice Ruins East
Return to Ice Ruins East; there is now a Sheegoth here as in Ice Ruins West. Get up to rooftop level as before, but stop just after passing through a hole in a wall. Look to the side to see a Spider Ball track, now follow it to collect a Missile Expansion.
There are more expansions to be found in the Chozo Ruins, but these are on the way to the next upgrades and will be covered in those pages.