PK group size limits via Royal Hunters

If 3 or more outlaws or murderers gather in the same combat-enabled
area, royal hunters of the realm will appear and attack them all.

Royal hunters of the realm are protected by the decree of the Princess,
and cannot be harmed. They will kill murderers and outlaws if they do
not surrender and allow themselves to be captured.

The goal of this system is to bring the murderer game back to its roots.
Whole guilds of murderers supported by countless characters and alts
were never meant to be unleashed upon hapless newbies. The murderer
system exists to allow the freedom to attack other players for fun and
competition for both attacker and victim. It was not designed to allow
a large group of drivers to PK en masse, trampling over newbies with
5+ reds.

This change will limit any PK attack to solo or pairs, giving builders an
actually decent chance to fight back.

Legitimate PK has always been about lone wolves or duos. This preserves
that legacy while removing the ability for a large group of drivers to
force themselves on everyone else.

Hunters are supposed to have the numbers advantage, and murderers
are supposed to be 'on the run' and always at high tension. This will
restore some of that balance.