Terrain Reshaping

When cast take two turns to reshape the terrain to whatever you like, you can create walls, spikes or even large craters. However, how intricate a design could be would be determined by a roll of a d20, a high roll means that you could make a bastion using the materials around you, but a low roll would mean the limit is a couple of hills. On the first turn nothing would happen but on the second all of the changed you have decided would come true. With this spell you would always have the advantage.