To reach Lavos, you must go to the Ocean Palace.
After the battle you can go back out to that save point to save and use a Shelter.
Use the portal thing in Zeal's room to get to the Ocean Palace.
Switch to Crono, Lucca, and Frog.
Talk to Mune and watch the scene. Then continue down through the door.
Here you'll fight Scouters (use Lightning), Red Scouts (use Fire), and Blue Scouts (use Ice/Water).
Go down to the center of the room, and fight the Scouters to get the chest.
Exit northeast. Step on the switch, then first beat the guy who's moving around a lot, and then beat the other one. Exit southeast.
Beat the monsters, then open the chest. Exit to the left (not northwest).
Take the diagonal path down and open the chest. Then, to be sure you avoid the Scouters, go back up the diagonal path, and this time go down along the edge that hugs the wall. Exit southeast.
You can avoid these Blue Scouts. Exit south, open the chest. Now just ignore the monsters and path below, and instead go back the way you came, into the big room.
From here go up, then quickly down the diagonal path to the left to avoid a fight. Then, up (you can go behind the column in your path) until you get to the northwest exit. Go through.
Hit the switch, and defeat the Jinn and Barghest the way you did before. Exit southwest, fight the Mage and Blue Scouts, then open the chest. You can exit right, through the wall, do so.
Go along the ledge that hugs the wall and exit southwest. You can avoid the Red Scouts here. To their left is a chest. From here exit south, then use the ledge that hugs the left wall. When you get to the bottom of the screen, there's a hidden passage in the wall to the right, to get to a chest (Demon Hit). Exit here and go back to the beginning of the ledge that took you here.
NOTE: If you don't plan on playing through Death Peak (where you get the BraveSword for Frog), DO NOT SELL the Demon Hit. In a New Game +, the Masamune disappears from your inventory (since it's a storyline item) so you'll need a powerful sword for Frog.
Now, go diagonally behind the Scout to the left, and around the edge of the platform until you reach a chest. Then, go back around avoiding the Scouts, and you'll want to go to the right, where there's a switch. Step on it, then go right, and all the way back to the big room.
Follow the path to the south exit.
You can ignore the monsters and just exit down the stairs to the left.
You can't avoid the next fight, so just go down and fight the Mages and Thrashers.
Down the next set of stairs are some jumping Thrashers, and if you touch any of them, you have to fight later on. They're hard to avoid, but if you can, run underneath when it's at its highest point. Then go down the rest of the stairs to the next area below, and fight any Thrashers that you touched.
In the next area below, run to avoid getting hit by the fireballs (which hurt you for 10 HP with each hit) and fight the Thrashers. Then head down the next set of stairs. The next fight is unavoidable, so fight and go down the stairs to hear from Masa and see another scene.
Continue down the stairs to the next area. You can avoid the Jinn and Barghest, but you'll miss the save point to their left, so it's up to you. Exit south.
Fight, then hit the switch, and you'll have to fight a few times as you head down. When you're done, exit north.
If you want a Magic Tab as well as more experience, go back and take the elevator back up, the Tab is to the left, then exit. You have to go down the bunches of stairs again, plus the elevator. When that's done, exit north.
Take either the left or the right path, beat the Scouts/Scouters, hit the switch that was behind them. Then take the other path and do the same.
Now step on the middle switch and go across the bridge and exit north. You can take the small platform back up by stepping on the switch at any time.
The next boss fight can be really tough, so you may want to level up on the elevator before continuing. It helps if Lucca knows Fire II, and it helps if Ayla and Lucca know the Dual Tech Flame Kick. It's also very helpful to have the magic-absorbing armor that can be obtained by opening the sealed chests with the pendant. Read the Break the Seal section for a list of the locations of the sealed chests.
Up in the next room, open the chest and save and use a Shelter.
Put Lucca in the third slot in your party (farthest from Crono.) Have Ayla as your third member. Put Ayla in the middle. Equip Lucca and Ayla with Fire-absorbing armor (Red Mail, Red Vest). Equip Crono with armor that reduces Fire damage (Ruby Vest).
The GolemTwins can be very difficult if you use a bad strategy. The method below should make the battle easier, although it's still a challenge, of course.
The GolemTwins change their attack mode depending on what they were just attacked with. Physical attacks make them use an attack type that will likely kill you in one hit. So, to avoid this, the strategy will involve attacking them with Fire spells.
Each GolemTwin has a Magic Tab that you can Charm. Before you can Charm them, you need to get them into Fire-attack mode to avoid losing the battle.
Wait for Lucca to get her turn to cast Fire II. If you put her in the third slot, she should be safe from the physical attack that the GolemTwins start with, giving her time to cast the spell. After she casts Fire II, she will be safe from any attacks that the GolemTwins might hit her with because of her fire-absorbing armor. Have her revive Ayla. Crono can stay dead if he was hit by a physical attack. You can revive him later if you want him to get the experience from the battle.
Now, if you want to get the Magic Tabs, wait for Lucca to be ready to attack, then have Ayla use Charm on a GolemTwin, then immediately have Lucca cast Fire II. This will keep them from attacking with their Physical attack.
After getting the Magic Tabs, have Lucca and Ayla hit them with Flame Kick over and over until the GolemTwins die.
Continue Through the Ocean Palace
Before moving on, go back and use a Shelter and save. Then go up through the top doors, talk to the Nu, then head up.
You'll most likely be beaten, unless you're playing a New Game +. If not, just let it beat you.
If you can beat Lavos now, do it for ending "The Dream Project"
When the time comes, have Crono walk up to Lavos and watch the scenes.
When you're back in control, I like to switch to Frog, Robo, and Ayla.
Now your party can be made up of whomever you like. This opens up some new triple techs.
In this hut, you can save and rest. Go out.
Go into the hut at the top to buy stuff from the Nu if you wish. Talk to both the Nu and the person, and then if you go back into the hut and don't move from the spot where you enter, the Nu will exit so you can get the Magic Tab.
Go into the Commons (foresty area) and go up to the top and speak to the elder. Our old friend Dalton shows up...