Does Charm moving a unit to a battlefield where there is an enemy unit trigger Surprise Defender for the unit that is moved?

No, moving an enemy unit with Charm does not make it a "surprise defender."

Here is the breakdown of why this interaction functions differently than a "surprise defense":

1. The Definitions

• Surprise Defense: This is a tactical maneuver (typically performed by a player on their own turn or in reaction) where a player uses an effect to move their own unit into a battlefield where an opponent's unit is already attacking, designating themselves as the defender.
• Charm: This effect moves an enemy unit. According to RiftJudge FAQ #7385 and #7275, when you use Charm to move an enemy unit to a battlefield you control, that moved unit becomes the attacker. You (the controller of the battlefield) are the defender.

2. Why it isn't a "Surprise Defender"

"Surprise defender" is a term specifically used when you voluntarily move your own units to engage in combat on a battlefield where you were not previously present. Because Charm forces an enemy unit to move, it essentially "drags" them into a showdown where they are the aggressor, not a defender reacting to an attack.

Summary of the Flow

1. You play Charm to move an enemy unit to a battlefield you occupy.
2. A showdown is forced (if the battlefield becomes contested).
3. The moved unit is designated as the Attacker.
4. You are designated as the Defender.

Because the unit moved by Charm becomes the Attacker, it cannot be a "surprise defender." It is simply the attacking unit for that showdown.