http://supercell.com/en/terms-of-service/

You agree that you will not, under any circumstances:

Engage in any act that Supercell deems to be in conflict with the spirit or intent of the Service or make improper use of Supercell’s support services.
Use cheats, exploits, automation software, bots, hacks, mods or any unauthorized third-party software designed to modify or interfere with the Service, any Supercell Game or any Supercell game experience or without Supercell’s express written consent, modify or cause to be modified any files that are a part of the Service or any Supercell game.