Hunting
From LSWiki
Whenever you are in combat and your opponent flees the area, you automatically begin hunting it. The next time the two of you meet, you will receive a free round of attacks. You may cease hunting an opponent, forgoing your free attacks, by typing 'stop hunting <opponent name>'. You may wish to do this if you want to stop fighting an opponent, particularly a player.
Note that hunting applies to all living things; running away from combat is therefore a bit hazardous.
You may find out what things you are hunting with the command 'show hunting'.