This song starts out very soft and easy, it slowly builds tension by adding more and more sounds/instruments. Not having drums in the beginning really helped build this tension because whilst listening to it you can notice it needs drums and at the climax they come in and release all the tension.
There are also small tension breaks throughout the middle part of the song, the slight pauses with a synth being pitched up before the drop comes back in.
The strongest example of tension and release from this song is at 3:33 where all instruments stop, a synth and light guitar play softly slowly progressing with the vocals, a drum roll comes in to build it up even more and is then released with a crash, or multiple crashes.
wobbly synths pitching up to build tension