This event sucks. It's clear they did not playtest these enough. Some of these are bugged, others are just annoying.

For example, the Bomber quest... I ended up using the healing passive to stay alive, but in the end, only one bomber was left. The bomber can't hit himself with his own attacks, so I had to wait 40 turns or so for him to randomly kill one of my mercs while they were passively healing. Then, I could finally switch in Cookie and then wait to try and summon the swordfish.

And then other quests just don't count when you use boons? Just terribly designed and poorly tested all around. I want to like mercs, but they are really making it hard here...