Heal and Res for Demon Army?

[Xargon]

Originally Posted by Karlos

Does that spell even work? Whenever I clicked on it, it said I can't do it or some such message.

It is supposed to use a luck rune, so if I wanna use it on Demonologists, I have to wait for their turn, so the spell can use up their rune?

No, you need them to have a luck rune. If you have some levels in the talent rune magic, your units start with the appropriate number of runes. To see which ones they have, look at the rune icon in the unit screen (where the status effects like buffs are displayed). You can use the spell Runic Word to give them more runes.
Note that Gift currently requires a luck rune to activate, but uses up a defense rune (if available). This will probably be corrected in some patch...