This came up in a game recently.
Can I play an interrupt enhancement during battle (e.g. Joseph in Prison), when my opponent's hero is IMMUNE to the BRIGADE of the interrupt card. In this example, the hero was immune to black (via Helmet of Salvation), so could I play Joseph in Prison (black) to interrupt the battle and remove him from the game? [It would seem wrong, because I would be "harming" him with a black card.]
Thanks