You could always just use the rules for diagonals on page 252 of the DMG

Jesus saves! Everyone else takes full damage

Thanks friend, doing it now!

And if you take 3 levels of armorer you can have your armor change to fit your new form to have a good AC and shoot lightning as you slither around as a robosnake

I have tried doing XP triggers before and I found it a little difficult to keep it fair between characters. If I were to do it again I would award the whole party XP when an individual fulfills a trigger.