Go all the way back until you get back to the mine. If you want to get the Red Ring, which is risky to get and not essential to finish the game, read below, otherwise go directly to the next paragraph. Go back to the area with the lava pools. Reach the space between the two pools, using the cart or the moving platform. It's time to use Freeon-Leon's special weapon. Use the frozen breath to turn the nearest floating enemy into a block of ice. Quickly switch to Shades to take advantage of its gliding ability and hop on top of it. Switch back to Freeon Leon and do the same with the next enemy. You will have to be quick, because the enemies thaw after a while. This is a technique you will need to master. It is not difficult to reach the door, but you will have to be very careful not to fall into the lava or you will lose a lot of life points. Enter the door and in the next room you will find a chest with the Red Ring. After getting it, go back following the same procedure. Use the moving platform to reach the right wall and climb up.
Exit the mine through the passage on the right that you entered the first time. This time, however, instead of using the springboard, continue to the right. Kill the slimes and the face you find on the path and you will reach a brick wall. Use Gil's bombs to clear the way and enter the door. You will find yourself on the edge of a precipice. You'll notice a chest on a ledge in the upper left and enemies flying over the void ahead of you in an ascending arrangement. To reach the chest you will have to freeze the enemy closest to you with Freeon-Leon's icy breath, quickly switch to Shades to jump on it, switch back to Freeon-Leon and repeat the process with the enemy higher and so on. What makes climbing very difficult is the fact that these enemies move up and down. You will therefore have to be very careful to freeze them at the right time, so that the jumps are not too high for Shades. A good strategy is to always freeze them when they are at their lowest point. You also need to be quick, as the enemies thaw after a few seconds. If you make a mistake, you will end up at the bottom and have to start all over again. Reaching the chest is not easy at all, but this is your only chance in the game to get the Water of Life, which will fill all your Life Containers. It is therefore strongly advisable to take it and save it for the end of the game, if you can. After grabbing it, drop to the bottom and continue to the right.
Now you will have to overcome an extremely difficult area. Ahead of you is a pool of lava, with enemies like the ones before flying just above the surface. The procedure to follow is the same: freeze them with Freeon-Leon and climb on the ice blocks with Shades. Again, you need to be quick and freeze enemies at the right time, preferably, when they are at the lowest point. Do everything with the utmost care, because a single mistake can be fatal. If you make a mistake here, you will inevitably end up in lava and lose 10 life points every instant, which will lead you almost surely to a game over. This is the most treacherous point of the game. After passing the first pool, you will have to pass another even longer one. Once safely on the other side, use Bop-Louie's suction cup to climb up. Proceed to the left. You will find two monsters that spit worms. This is a good area to restore energy by repeatedly killing these worms to gain crystals. However, it takes time and patience. At the end, enter the door and get ready to fight another boss.
This boss is very unusual. It is encased in sturdy armor and if you jump on its head you won't get any results. The only way to damage it is to use Bop-Louie's or Shades' special weapons. You will then have to load your weapons, while avoiding both the boss, who runs back and forth around the room and the spears that will fall from the ceiling. If you coordinate your movements well, you should be able to do it without taking too much damage. When you hit the boss 6 times with Bop-Louie's special weapon or 3 times with Shades's, its armor will break. The boss will be reduced to a helpless cat, which will no longer move, nor will it attack you in any way. Jump on its head 8 times to eliminate it permanently. Continuing on the right you will find the Blue Key, the most difficult to obtain.
You will now have to go back, passing over the dangerous lava pools again. Be very careful. Once you have passed the pools, climb to the upper level and enter the door, to leave this treacherous area.