Pro as heck tip for next ranked season
Dodging doesn't lower your MMR. It only lowers your LP.
During placements, dodge literally any game you have a really bad feeling about (mostly OPs/trolls/comps/lane counters).
You lose absolutely nothing for it until you're placed and start gaining LP because you cannot gain/lose LP during placements.
Good luck in season 7!
_P.S. Dodge any game you feel uncomfortable about, tbh. Better to lose 3-7 LP than ~15-25, losing some MMR, and tilting hard. You can dodge 5 games you have a bad feeling about and still be better off than going through with one of them that you think would have lost. Why? Because you still have your MMR intact, and you'll climb easier for it. _