Is recalling a unit from a battlefield considered a move in the context of cards like Stellacorn Herder and Travelling Merchant, i.e., just moving back to base not caused by the effect of a spell?

No, recalling a unit from a battlefield is not considered a move, regardless of whether it is caused by a spell effect or by the game rules (such as returning to base after failing to conquer).

According to Rule 451 and FAQ #7722, "Recalls are not Moves." This distinction is fundamental in Riftbound:

  • Stellacorn Herder: Because its ability triggers "When I move," it will not trigger when the unit is recalled. Recalls do not satisfy move-based trigger conditions (see FAQ #9481).
  • Traveling Merchant: Similarly, its ability triggers when it moves. If the unit is recalled, the ability will not trigger.

Key takeaways:

  • Recall vs. Move: A "Move" is a specific game action (Rule 440). A "Recall" is a distinct game action that relocates a permanent to its base (Rule 450).
  • Triggered Abilities: Abilities that trigger on a "move" will not trigger on a "recall."
  • State: Per Rule 453, a recall does not change the state of the unit (e.g., it remains exhausted if it was exhausted, and it retains any buffs or debuffs).

Whether the recall is forced by a spell (like Zhonya's Hourglass) or by the game state (failing to conquer a battlefield), it remains a recall and is never classified as a move.