Conquer
The party must defeat or otherwise remove all enemies on the battle map. This is the most common objective for clashes, and it can occasionally appear in dungeon battles.
Eliminate X
To accomplish the Eliminate objective, the specified objective unit (or units) must be defeated or otherwise removed from the battle map.
Survey
The party must fully explore the battle map by gaining all required skyshards. The default number of required skyshards is 3, although the encounter may specify a different amount. The encounter is failed if the party does not gain all of the required skyshards. This is the most common objective for delve battles found in guild quests.
Uncover
The party must fully explore the battle map by gaining all required skyshards—by default 3—and then successfully retreat. If the party retreats before fully exploring the battle map, the encounter is failed. Unlike other objectives, the party gains XP from each skyshard it acquires in the delve—up to that delve's required limit— so long as the entire party is not defeated, in which case no XP is gained. This is true even if the party retreats before it has gained all required skyshards (see Retreating from Battle).