no wtf! blast beats consist of alternating usually snare and hi-hat, or it can be a ride cymbal or even the bass. the bass can also come in on or off the beat for emphasis, as well as the ride or hi hat, whichever isn't being used.
To put it into layman's terms,
Intro to Into the Shadows = Blastbeat.
Downfall, Touch Like an Angel of Death = Double-bass.