After you find some Dactyls to fly around on, you can reach the Reptites' hideout in Tyrano Lair.
Go to Tyrano Lair
Tyrano Lair is in the lava field southeast of the Dactyl Nest. You can press Select to view the world map and press B to close the world map. When you are above the platform with the building in the lava field, press A to land there.
Inside, go north and enter the open skull, then go down the stairs. Defeat the Reptites, then check on the switch to the right of the bars to open the cell. Go east and defeat the Reptites at the stairs, then go down the stairs.
Defeat the Reptites in front of the cell, then check on the bars to talk to Kino. There will be a cutscene. Before you follow him, go into the cell and open the chest (Mid Ether). Then leave the cell and go back up the stairs. Follow Kino back to the entrance, where he will open the other skull. Go through the skull that he opened and go up the stairs beyond.
Go east and step on the switch on the floor to open a trap door beneath the monsters. Then go south through the door. If you go directly east, you can avoid a battle here. In the next room, don't open the chest on the right or you will fall through a trap door and have to battle some enemies; if this happens, just open the cell after you defeat the enemies and go west to return to the dungeon entrance, then go through the skull on the left and go up the stairs there. Otherwise, if you didn't fall through the trap door, open the chest on the left to get a Full Tonic, then make your way back to the room where you stepped on the switch to make the monsters fall through a trap door.
Go to the left side of this room, step on the switch to open a trap door beneath these enemies, then go south. You will battle some Reptites outside. Go through the door on the left.
In this big room, certain tiles will warp you around when you step on them, so there is a specific route to get all of the treasure and then reach the exit.
First, walk east until you're against the east wall. Go north past the first gap in tiles, then as soon as you are past the second gap in tiles, walk west to be transported. Go north and open the chest (Revive).
From there, go south about five tiles, then east onto the tile that sticks out at the corner near the chest across the gap. You'll be transported. Go north and open the chest (Meso Mail).
From there, walk west across the small bridge of tiles until you're transported again. Go north and open the chest (Tonic).
Walk south from that chest, and when you reach the edge, go west, then south down the bridge of tiles, and open the chest there to get a CeraTopper.
From here, go north until you can go west. Go west and you will be transported to the stairs that lead to the next area. Go up the stairs.
Be sure to equip the armor that you obtained.
The path leads outside. If you want to avoid the monster encounters here, stay near the north wall. When you are near the locked door, go south and walk east along the south edge of the small ledge. Continue walking east along the south edge, but when you are about halfway along the longer edge, go slightly north, then east. From there, you can go north to the door.
Step on the switch on the right to open the skull. Go through the skull and check on the wall switch. Then go back outside.
Go west to the middle door, battle the monsters that attack, and go through the middle door.
Walk around Nizbel and stand in the save point to use a Shelter and save the game. Try to use the north exit and you will be attacked.
Have Crono and Ayla attack with Volt Bite (a.k.a. Thunder Chomp in some versions of the game). It lowers Nizbel's defense. Leave Robo to heal whenever Nizbel releases the electric energy, then repeat. Keep your HP above 200.
Tyrano Lair, Part 2
Use the save point and a Shelter again, then go north up the stairs to go outside.
Go to the east side of the area and go north through the door there.
Ignore the switches on the left and right. Step on the northernmost switch and a save point will appear. Check on the skull's teeth to open it, then go through and open the chest to get a Full Ether. Check on the wall switch, then go south and use the save point, then go south to go back outside.
Go west, then north and through the middle door. Go north to find Azala. After the cutscene, open the two chests next to the throne (left: CeraTopper; right: Mid Ether). Then go north through the door. From there, go north until there is a cutscene.
Azala and BlackTyrano
Defeat Azala first by having Crono attack with Lightning (not Lightning2). Ayla should not attack until Azala is gone. Keep your HP above 250. If BlackTyrano eats one of your party members, have Robo heal him/her right away.
When Azala is gone, wait for BlackTyrano to "remove def" and "store pwr" (which he may do before Azala is gone). When he does this, a countdown will start. Before the countdown ends, attack as many times as you can with Crono and Ayla's Volt Bite, and leave Robo to make sure everyone's HP is above 350. When BlackTyrano uses his fire attack, have Robo heal everyone up, then wait for BlackTyrano to remove def again before you start attacking again with Volt Bite.
After the battle, you can optionally go southeast to the Dactyls if you want to go back to the village to heal up or buy supplies. Otherwise, go to the crater in the lava field where the Tyrano Lair was. Enter the Lair Ruins and there will be a cutscene. Check the gate to go through to a new area.