If you score on a battlefield by holding, then leave with all units, and re-take it with Kai'sa in the same turn, does her conquer ability trigger?

Ruling: No, Kai'sa's conquer ability does not trigger. You cannot conquer a battlefield you've already scored on in the same turn by holding, because conquering requires scoring a point and you can only score once per battlefield per turn.

Sequence:

• You score by holding the battlefield
• You leave the battlefield with all units
• You move Kai'sa back to the battlefield
• You take control of the battlefield but do not conquer (no point gained, no conquer triggers)

Nuances:

• You do still get conquer triggers when you can't score due to the last point rule (different from the already-scored-by-holding scenario)
• Taking control of a battlefield is distinct from conquering it; conquering only occurs when you take control AND score a point