This variant was designed for the solitaire game, but it should also work with the regular multiplayer game. It's recommended for lower player counts.
At the start of the game, set aside two zimbies of an unused color. Red works well.
This variant has two parts:
While the King is alive:
Thugs behave normally with one exception: when a zimby column breaks an elemental seal, the two thugs nearest to the shrine containing that seal immediately move 1d6 spaces toward that seal. This movement can even be in a widdershins direction, i.e. against the "current" of the normal thug movement path. This interrupts the current Shaman turn and is in addition to the normal thug movement for that round. Thugs that enter combat range of a zimby column become combat locked with that zimby column but do not immediately attack (they will during the thug turn).
After the King dies:
Thugs behave normally until a zimby column picks up the Cannibal Crown. Immediately after a zimby column picks up the crown, the two thugs nearest the crown are promoted to elite guardsmen. Place the unused zimby tokens underneath them to mark them. During the thug turn, elite guards will move 2d6 spaces directly toward the crown-holder rather than attempt their normal patrol routes. Despite their promotion, they aren't clever enough to avoid obstacles, and behave essentially like zombies except that their target is always the crown-holder. The behavior of the other two thugs depends on the game mode:
Multiplayer: The remaining thugs will randomly patrol the outer quadrants. Each thug immediately teleports to the entrance to a random outer patrol route (reroll if you get a route that's already being patrolled). The thug is said to have "completed" its patrol when its path once again touches the inner patrol route. At this point, the thug immediately teleports to a new, random outer patrol route.
Solitaire: The thugs will proceed toward their flanking points by the most direct route possible. This might mean moving against the normal "current" of movement on the patrol route!