I want magic abilities to be represented by an item, something like 'Magic Spell'. You have a magic reserve as a variable, and whenever you use the spell, it goes down by five. If it reaches zero, it starts taking five health instead. This is supposed to represent death if you exhaust yourself by overusing magic. I'm assuming that in order to achieve this, I would have to use scripting, which I'm okay with.
Basically, each time you use 'Magic Spell', Reserve goes down by five. If it hits zero, 'Magic Spell' takes five from Variable2.