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...You may discard this card from your Magician during battle to capture up to two human Heroes...
YourSeveral cards in Redemption® refer to cards that are “your” cards (e.g., your Priest, your Heroes, your demons, your warrior-class Evil Character, ). The possession and control of a card is implied by the use of the word “your”.
I would say it's a wise move just because then you're making a very powerful character (their MC endowed magician) vulnerable to discard by your opponent.