I Hear 4 sounds here. The "Echo" introduced at 0.01... the "Thunder" introduced at 0.11, The "Scratching" at 0.16, And the "Knocking" at 1.17.
The Echo is a perfect background feel to the song. And the Thunder helps give a slight "Terminator" feel to the echo. I Feel the Knocking was extremely beneficial to the song as its what really brings the "Tension" to it. The Weak link I feel here is the Scratch. At points like 0.48 when your speeding it up It sounds good but its still repetitive... Perhaps adding a variant(s) would help. Think of adding a "Creak" add-on to that scratch noise? Or perhaps have it fade out slightly at the end, like its going away from the listener.
Fairly impressive track. good work.