Crono and the party on the world map, walking near Arris Dome in a blasted landscape
Chrono Trigger owned by Square-Enix. 
Images used for educational purposes only.

Part Seven: Abandoned Sewers, 2300 AD

Arris Dome, 2300 AD

- Another bleak locale. The folks in here don't have much of use to say, other than to comment that one of their number has gone into the basement and hasn't returned. Guess where you have to go? Use the Enertron in the north, speak to the little girl in the west for wares and use the save point, then step down the ladder in the middle of the room.

- The next two rooms are of little use right now. Cross through them and make your way to the far north, along the iron beams. You'll trigger an alarm of sorts, and once you do -

Crono, Marle, and Lucca battle the Guardian beneath Arris Dome in 2300 AD

Guardian

Yep, boss time. The Guardian is accompanied by two Pods, both of which assault your characters, and you need to take down all three enemies to finish the fight. The Pods will assault your characters individually, while the Guardian will sit largely comatose for most of the fight, only waking up to revive destroyed Pods after a certain number of rounds. That said, if you attack the Guardian directly while the Pods are still alive, you'll incur a painful, immediate, all-hitting retaliatory attack that really smarts.

Your strategy is simple enough. Start by wiping out the Pods with regular attacks, as your special attacks aren't terribly effective against 'em. Don't bother healing unless you really really have to. Focus every move on bringing them down, one-at-a-time. Once the Pods are gone you'll have five rounds to deal as much damage to the Guardian as you can muster. Use this time to heal with Aura Whirl quickly, then bring everyone to bear on the Guardian. Smack it 'til it dies. If you're fighting at full effectiveness you should only have to suffer a single revival of the Pods before wiping out the Guardian.

Crono and the party watch a recording of Lavos emerging from the earth in 1999 AD and destroying the world

- Enter the back room after beating the Guardian for a sad little cut scene, then check the man inside for a note regarding the rat statue you passed earlier. Check the box in this room for a Mid-Ether, then head back the way you came.

- Back on the girders the 'statue' will be revealed as a live rat. Chase it down (simply keep directly on its tail and keep tapping the button 'til you catch the rascal) and it will give you a code to get through the door in the next room. The code will change depending on your copy of Chrono Trigger; for the SNES and DS versions you'll have to hold L and R and press A, while the PlayStation version requests L and R plus X instead.

- Pop open the door, return aboveground to heal, then enter the depths of Arris Dome. Straight ahead in the next room you'll find an Exterminator circled by two Rats. Take out the Exterminator, as the Rats are nothing to you. North of this little band you'll find a chest containing a Mid-Ether.

- Along the walkways to the left you'll run into two bands of Bugs. They're nothing to you. Wander south, then right, then north.

- This next room is full of baddies, notably the new Version 2.0s, but you can bypass them all rather easily. Your destination is a catwalk along the left wall that leads to a door in the far north. (Though if you check the northeast side of the room you'll also find a panel where you can use the same code that got you down here to open a path to a nearby, locked door. Sigh.)

- A lengthy cut scene waits behind the door to the north. Yep, you're in the far-flung something-or-other. Bad times.

- Filled with determination, head back upstairs. Another cut scene follows, and after it's done you're finished with Arris Dome. Heal up and head out, a new Jetbike Key in hand.

Part Nine: Proto Dome, 2300 AD