I am planning on doing some 10 mask runs but I want to know if the deku mask counts towards the mask total.

As far as I know, Deku Mask doesn't Count. Not Sure tho, I'd suggest you Go to the Majora's Mask Speedrunning Discord which is Linked on the Side Bar and ask there, I think you get More Help There than here

Deku Mask counts

@gc_one2 didn’t know that. Thanks for the Reply tho

So it does!?

Deku mask does count as a mask. Same with any of the other transformation masks.

Yup, here you have the actual answer. It does count. Sorry for the last misinformation.

Good to know. Thanks!