Quest
From AmtWiki
A goal-oriented battlegame that usually involves a series of connected goals or activities, and often includes Monsters and Relics and Roleplaying.
From the Rulebook
Quests are simply special battlegames. The reeves and designers of these make special rules, and often have special monsters, which are not used in the standard games.
For a list of Quests that you can run, see Quest Write-Ups.