In WoME the Treebeard card states, "Earthborn. If Treebeard is in a battle..." What constitutes Treebeard being in a battle?
1. He is the Ent that is required to be removed for an attack to take place. 2. He is in the Entwood (Fangorn) 3. He is adjacent to the defending force the Ents are attacking 4. He is anywhere in the line of Ents from Fangorn to the attacking area. 5. Something else
It's 5 (something else). A "battle" occurs between two Armies, so an Ent attack is not a "battle". As with any other Character, Treebeard is in a battle if he is in the same region with the involved Free Peoples Army.
By the way, Treebeard is not an Ent for the purposes of moving and attacking with the Ents. An Ent Faction figure represents a collection of multiple individual Ents, just as an Army unit represents a collection of individual soldiers. As a Character, Treebeard is no more an Ent Faction figure than Boromir is a Gondor Army unit.