Boomsday bug Doctor Boom shooting too early

I am playing the Boomsday puzzle lab “Mal’ Ganis and Me” and I am finding that doctor boom is killing me even though I am still able to play cards. After I kill the Turret Sentinel, it refreshes my crystals, but the minute I play soul repressor, Doctor Boom shoots his laser at me even though I still have 5 mana crystals. I can’t find any other solution to pass the level with this bug. I am trying to get the card back.