At level 85 the ten-twelve first bubbles mean everything. If you screw them up, the level is unlikely passed.
Like a few other levels, the infection at level 85 needs to be stopped by any measures necessary! That if you have any urge at all to see the last row of bubbles in the ceiling. If you have memorized them or otherwise (otherwise would in this case be Charm of Scrolling) can figure out howto shoot them, just skip the rest of the guide, you probably can’t benefit from it.
The level is alright and absolutely playable without Charms. Not a level to love though. If you have considered buying the Charm of Healing, now is a good time to purchase. That will give you a good advantage and you can ease a bit, focusing on the Bombs.
I made a game strategy picture, to show where the critical line for the infection is. It comes upon you all to sudden. It seems drastic to forget all about collecting score and forget about not hitting the Bombs, but those things won’t be worth anything unless you can see the ceiling.
Best luck with level 85!