Spells
From Hulks & Husks Wiki
Planescape includes a variety of setting-specific spells. I haven't found any 5e conversions, but many 2e spells are generally usable "as is" (e.g., when no damage is involved). Warp Sense is very useful to planewalkers. Casters may also be particularly interested in:
- Gate Seal
- Gate Ward
- Portal Alarm
- Portal Beacon
Here's a nice 3e conversion of all the spells: http://www.enworld.org/ericnoah/conversions/planewalker/spells.html
(I have the 2e Planewalker's Handbook if we need the original source.)