Iron Bark
When this unitUnitUnits fall under 2 categories: party and enemy. These 2 categories, in relation to one another, are referred to as opposing units. is dealt damage by non-adjacentAdjacentHexes are adjacent to each other when they share a common edge. Units, overland tokens, chips, or features in adjacent hexes are adjacent to each other. Battle map tiles are adjacent when at least 1 hex on a tile is adjacent to at least 1 on the other tile. units, its defense is increased by 1 for that engage.
How does Iron Bark work with the Bow skill Volley?
Any restrictions regarding which units a die can be resolved against (for example, if a result requires adjacency) are assessed at the time the die is resolved, not at the time the damage is applied. Volley damages an adjacent enemy. Therefore the enemy must be adjacent at the time that Volley is resolved - even if that damage is pooled and then later applied after you are no longer adjacent.
Iron Bark wouldn't trigger because you were adjacent when the damage was dealt.
Source