Mount LUKS

Set up LUKS for the volume:

sudo cryptsetup luksOpen /dev/sdXN examplename

This will prompt for a password.

Mount LVM

sudo pvscan
sudo vgscan --mknodes
sudo lvscan

If the volume isn’t active:

sudo vgchange -ay <VolumeGroupName>

Get the device name from the lvscan output:

mount /dev/mapper/whatever /mnt -t btrfs -o subvol=@