Pedals that stack with the Old Blood Noise Endeavors Flat Flanger

Xotic RC Booster

Xotic RC Booster leans toward transparent, and that's a real, usable character to pair with

Beetronics Buzzter Boost Preamp

What Beetronics Buzzter Boost Preamp brings here leans toward transparent — that's worth building a pairing around

Benson Amps Delay

Keep Benson Amps Delay after Old Blood Noise Endeavors Flat Flanger in the signal chain, clear of Old Blood Noise Endeavors Flat Flanger's own gain stage — goes in the amp's FX loop (or last, into a clean amp)

Boss DD-7 Digital Delay

Run Boss DD-7 Digital Delay after Old Blood Noise Endeavors Flat Flanger in the signal chain, clear of Old Blood Noise Endeavors Flat Flanger's own gain stage — goes in the amp's FX loop (or last, into a clean amp)