Need Help figuring out a statistics problem

I'm not sure that I am doing this right. I am trying to figure out the odds of being hit X time in a row during a fight where a boss swings Y times.

Figuring out the probability of X times in a row is easy. If you want to calculate out the chance of getting hit 5 times in a row and your avoidance is 38.32% total, then the chance of getting hit 5 times in a row when swung at 5 times is 8.93%. But what are the odds of getting hit 5 times IN A ROW when swung at 100 times and could someone please provide the formula they used to figure it out. Right now I'm getting an answer of about a 99.9874% chance that you will be hit 5 times in a row on a fight that a boss swings at you 100 times.

Can this be right?

Current formula for the probability is (1-(1-%avoid)^x))^(y-(x-1)) that you won't get hit x times in a row on a fight y hits long. So then 1 minus all of that is probability you will get hit in a row x number of times in a fight y hits long.

It feels like I'm doing something wrong.