i think it'd be insane. champions are overpriced compared to other cards due to their stay in play / guard nature. if by defeating them they become scrapped, you'd be inclined to never ever buy them (at current pricing).
How about you can choose to sacrifice a champion to reduce more damage?
In normal case, when a champion with 5 defence is stunned, it prevents you from taking 5 damage. If you choose to sacrifice it, it prevents you from taking 5 x 2 = 10 damage.
Good to try?