Special Maze Challenge, Traverse Lava

This room will be a room filled with lava
The only way across will be if the player is wearing a special armor boot named "ICE BOOTS"
First we should place a "Beware of Lava" sign next to the door:

Next we need to fill the room with lava when the player is in the doorway
This code will execute a server fill command when the player is at a specific location

Next we need to change all lava to ice when the player is wearing boots with the custom name: "ICE BOOTS"