how do you insert the voice, what you use?

za warudo over heaven - freak show (slowed)

this track is from ,,Saturny'' on youtube 
go check it out https://www.youtube.com/watch?v=7nWvmPkVzNU&t=4s

Luci4 - BodyPartz (King Crimson Remix)

Song is about a divided kingdom falling apart