I know how it feels when someone steels trolls griefs your base because this happened to me I suggest this should be in rule and if anyone does it give them just a kick not a ban because a lot of these happen in anni or anni beta who agrees ?
-1 This is already suggested and denied many times because it can be abused. Also, team trolling is allowed at the moment. By the way, other user has suggested another way to prevent team trolling: http://guildcraft.org/threads/anni-team-trolling-prevention.16377/
Uhm, Instead of punishing them, you should suggest something that might prevent them from doing trolls. Dude, violence (lol) is not the answer. Trust me, "Mothers knows best"