The legend Ivern has an effect 'it can be swapped back when scored'. What does this mean?

When you use the ability of Ivern, Green Father to replace a battlefield with a Brush battlefield token, that token carries the text: "When you score here, you may replace this with the battlefield it replaced."

In the context of the game rules, this process is known as "Swapping Back". Here is exactly what that means for your game:

1. What happens during the "Swap Back"

When you score at the battlefield location where the Brush token is currently present, you have the option to trigger the "swap back."

• The Brush token ceases to exist.
• The original battlefield card that was replaced is returned to that exact same battlefield location.
• The original battlefield inherits all current effects, statuses, and conditions that were present on the Brush token (per Rule 438.7.b).

2. Strategic Context

• Reversibility: You are not permanently stuck with the Brush token. If you find that the passive bonus provided by the Brush (giving Bird, Cat, Dog, Poro, and Ivern units +1 [S]) is no longer beneficial, or if you need the original battlefield's effects to win, you can revert the state of the battlefield upon scoring.
• "Here": The ability is location-specific. You can only "swap back" the Brush token at the specific battlefield where you just performed a score action. You cannot swap back a Brush token at one battlefield by scoring at a different one.

3. Important Clarification on Rules

According to the Rules FAQ Clarification (2026-04-29):

• A replacing game object (the Brush token) inherits all statuses and conditions of the object it replaced.
• When you "swap back," the original card is returned to the space the token occupied, inheriting all current effects and statuses (including any temporary battlefield effects applied while the Brush was there).

In short, "swapping back" is a mechanic that allows you to undo the replacement effect and restore your previous battlefield state whenever you score at the location of a Brush token.