How does Sett Legend work, specifically when does the 'ready me' ability trigger?

Ruling: Sett Legend readies itself whenever you conquer a battlefield (take control via combat or enter an empty battlefield and score a point). This allows you to use the first ability again, which requires exhausting Sett.

Sequence:

• Exhaust Sett Legend to use the first ability (save a character from dying by exhausting and returning it to base)
• When you conquer a battlefield, Sett Legend readies
• You can now use the first ability again if needed

Nuances:

• The ready effect applies to the Sett Legend card itself, not to champion units next to it