Can Emperor's Divide move units from different battlefields back to base?

Ruling: No. Emperor's Divide can only move units from a single battlefield. The card text specifies "any number of friendly units at a battlefield" (singular), meaning you must choose one battlefield and move units only from that location.

Nuances:

• If the card were intended to affect multiple battlefields, it would use plural wording such as "at battlefields."
• Units moved by Emperor's Divide retain their current state (Ready or Exhausted) when they arrive at your base.