I used to think that all that happened in that scripted event was that Stitches would spawn and just to to Darskshire to die.
But the whole thing involves a lot more scripts that I expected.
First off following the player delivering the translated letter to the mayor, he proceeds to order a watcher to inform the commander and raise the alarm
After the commander the watcher begins a marathon that lasts halfway the zone during which he yells at each crossroads to alert the watchers in the zone.
That first watcher eventually stops at the watcher camp the the middle of the zone and waits with the rest.
Meanwhile at some point after that, Stitches spawns near the Embalmer as a neutral mob (as to not kill people who cannot avoid him at this point) and starts moving towards the main road.
When Stitches reaches the road, the gloves are taken off and he is hostile now as he starts to make his way to Darkshire.
But the watchers are ready now, and they are ready to lay down the lives to put some hurt on the abomination!
Along the road they have formed two defensive lines consisting on 4 watchers each.
So on his way to Darkshire, Stitches get to cut down up to 8 watchers who also slow him down so the players can run to Darkshire.
While engaging these watchers he also makes emotes like roars and “Darkshire, I hunger!”
The show ends when he gets overwhelmed by the defenders at Darkshire.
Seriously this is really detailed and well made for the standards of the classic game. Well done to the original dev team!