"Find a way to destroy the omnibuses" is a mission objective in Sequence 5 / Memory: Friendly Competition
Walkthrough[edit]
Head over to the right and recruit the Rooks. Have them hold position.
Climb up onto the wall nearby the Rooks. Take aim at the brazier nearby the group of Blighters. Fire off a Hallucinogenic Dart into the Brazier to get 2-3 of the Blighters with it..
Climb up onto nearby building after that. Turn to the East and look for some more Blighters. Once again, fire off a dart into the Brazier.
Head to the Southern end of the warehouse and perform a leap of faith into the nearby haycart. Lure the nearby Blighter using a whistle.
Having eliminated that guard, you can head for the cart that he was protecting.