Another Element Puzzle

Once the 4th gallon of water was placed in the basin, the fountain began to fill faster, and faster, until it was overflowing. As soon as any of the water touched a statue, it melted away. Once it hit the wall of fire, immense billows of steam began to fill the room, obstructing vision and breath.

Recognizing a newly visible vent, the party quickly escaped through it. Unfortunately, it acted as a chimney, funneling the steam up through it, making breathing all the more difficult and as it condensed on the walls, making it difficult to crawl up the slight incline.

Leading the way, Rudy reached an intersection, the tunnel split, heading up one way, and down another. Attempting to climb higher, Rudy was thwarted by the wet walls and massive gusts of wind. Realizing they could only head down, the heroes did. The farther they descending the more the wind increased to the point they were pushed, even flying when they spotted a wall with nothing in front of it. Launched across the tunnel they slammed into the wall, taking damage, and then fell another 30 feet landing in a small room with 4 bowls, one in each corner.

Etched into the wall was the verse:
Three you have faced,
The fourth awaits,
Fill the bowls,
And face your fate.

Alexander figured out they had already faced fire, water, and air, so the heroes placed dirt from the floor into the 4 bowls and a hallway appeared before them.