The party is being stalked by a pack of velociraptors. They must all make a Perception check (DC 15) to notice that they are being hunted. If they succeed they may immediately begin the escape portion of the encounter. Otherwise proceed to combat.
The party is ambushed by 3d4 Utah Raptors (Hook Horrors) in a courtyard between several large buildings. Alleys lead off to in the cardinal directions. At any time during the fight a character may attempt to escape by running at least 40 feet down one of the alleys, leaving the battle map. This character cannot return to combat and proceeds to the escape portion of the encounter.
The each party member must make 3 successful checks to either run (Athletics/Acrobatics) or hide (Stealth). Using skills such as Survival or Nature can provide advantage to the check made by another character.
After each failure one of the velociraptors catches up with them and makes a multi-attack against that character..