Basically echoing what Lutrus said.
PG has gone on the record in saying it should work in at least one case for Adaptive resist. I believe they made a similar statement about adaptive flak resist. Although I believe they also have claimed it didn’t work.
So it’s a mixed message and I’ve seen zero definitive evidence to show it for sure does or doesn’t work. Resists runes are hard to prove due to their small increase and limited ability to test, and large amount or damage flaks produce
Likely someone could do the math to find a matchup that SHOULD make the difference between a number of tower shots before the dragon dies and prove that with the rune it took one more shot, but it’s a lot of work for something that won’t matter much.
I rarely use resist runes. And I don’t use them on dragons with adaptive resists