When there is a "/" it means just strum that chord once/quickly go to the next chord.
The Strumming pattern is pretty easy to follow along with.
Capo 1
Intro: Mute - then Am C Am C Dm C Dm Am7/C/Em/Am
Up with your turret
///
Aren't we just terrified?
///
Shale, screen your worry from what you won't ever find
Don't let it fool you
Don't let it fool you...down
Down's sitting round, folds in the gown
Sea and the rock below
///
Cocked to the undertow
///
Bones blood and teeth erode, with every crashing node
Wings wouldn't help you
Wings wouldn't help you...down
Am C G (unknown picking pattern)
Down fills the ground, gravity's proud
You barely are blinking
///
Wagging your face around
When'd this just become a mortal home? Now
Won't, won't, won't, won't
Won't let you talk me
Won't let you talk me…down
Will pull it taut, nothing let out
And that's all I got for now.