Propa Gandake (MP23-EN131) [25th Anniversary Tin: Dueling Heroes Mega Pack]

Once per turn, if you control a monster(s) whose original Type is Beast, Insect, Plant, or Rock: You can declare 1 of those Types you control; this card becomes that declared Type. If this card has applied this effect, also apply the following effects while it remains in the Monster Zone.
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• All face-up monsters on the field become the same Type as this card.
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• Monsters on the field with this card's Type cannot be targeted by either player using the effects of monsters your opponent controls with that same Type.