After defeating the beasts in the underground, you can climb Mt. Woe.
Before moving on, go back to Algetty and rest at the Inn, and save.
Then go back to the Beast's Nest and up that chain where you fought the Mud Imp and Beasts.
Change your party to Crono, Ayla, and Robo.
Fight the Rubble to the right if you want. Rubbles give you tons of experience and tech points, but they lock all techs so you have to beat them with physical attacks, and you usually will miss. Plus, it runs away eventually. Most of the Rubbles on the mountain disappear after you fight them.
Go north, beating monsters on the way, and get the Lode Helm. Then head back to where you entered, and go across the chain to the left. Follow the path to the next area.
There's a Rubble to the left you can fight if you want. Then go right and up where you'll fight Gargoyles.
Above that there's a hard to see save point. Go up from there, and you'll fight. Whenever you're fighting multiple enemies and some Gargoyles, beat the Gargoyles first. Then go across the chain to the right.
The Rubble here will reappear if you beat it and leave the screen, so if you want to level up in a hurry, use this guy.
Open the chests, then go back across the chain to the left. Go left from there, ignore the slope up, and continue left to a chest that you have to fight to get.
Then go back to the slope and up it, and head around the left. From there just follow the path. There will be a chest above you, get it, then go across the chain to the right. Continue on, using the chain that goes down.
Go straight down from there for a Rubble. Then go back to the chain and head right to fight, then open the chest and head across the chain going right.
Go up for the chest. Head right and across the chain below the monsters for a couple chests (one you have to fight for). Then go back to the monsters and try heading up the chain, and you'll fight.
Go up the chain, follow the path and fight the Rubble if you want, then head down if you want a Shield and a Shelter (you have to fight). Then head right across the chain. Fight the Gargoyles, then there's a save point to the right of the chain leading up. Use a Shelter and save, then head up.
The path here is straightforward, just continue and open the chests. There's a Magic Tab in the bottom right corner of the screen.
Now head up that chain, and you can change your party if you want. Robo and Ayla are good. Before doing anything else, equip everyone with fire-protective gear, like Red Mail, Red Vest, and Ruby Vest. When you're ready, check on the block of ice.
First keep using Falcon Hit on the hands to get rid of them, then attack the head with Volt Bite. Leave Robo to heal. Whenever the hands are revived, kill them again with Falcon Hit.