Tunnel

Create a 8 by 8 feet tunnel through any dirt, clay, stone or any of its other forms for up to 50 feet, as it uses 1 foot per foot. You can do the same with iron or steel but it uses 3 feet of power for each foot tunnelled.

At higher levels: If a level 3 spell slot is used, you can tunnel for up to 75 feet and it becomes a 10 by 10 foot tunnel as well. If a level 4 spell slot is used, the tunnel can extend for another 25 feet, totalling at 100 feet, and you can tunnel trough iron/ steel for only 2 power, rather than the previous 3.