Summons the town guard. This command can only be used against monsters
that attack you (unprovoked) on the streets of Elfhelm. It does not
work outside of town, nor does it work against monsters that you
have attacked (or defended yourself against).

So, if you wander into a room and get attacked by an evil monster that
you can't deal with, summon the guard. Or, if you accidentally yell in
a room full of monsters and they all attack you, summon the guard.
