After a million tries, I managed to boot into recovery. Thakfully, I had TWRP, so all I had to do was restore a backup.
Why don't newer versions of Android like custom densities? (and is there any way to get a custom density working?) I almost bricked my Nexus 10 the same way, just by changing the density. On Gingerbread, I could change my density to just about anything and I could reboot and see the effects. It seems Jelly Bean/Kit Kat has no support for it at all.