Music without lyrics usually. A lot of break core, sometimes lo-fi beats or video game music. I struggle to write with songs with lyrics because I'll be paying attention to the lyrics while also trying to write.

It's also usually for when I'm trying to push myself to write or am writing something intense. Gets the blood pumping. Interestingly I have play list for a lot of my characters too but usually those are just for me to listen to while I day dream or think of my reply.