I see a buff to this spell. Can this spell be arcane as might be useful for flying unit with no ground presence. All other amii spell become arcane, spirit gate could be a spell since u need ground presence to use it, while tranquility could be more useful as arcane. 

I think a problem with Amii spells is that the dual offensive/defensive nature of them makes it hard to decide between arcane and spell. When they are arcane, you have an offensive spell that doesn't need ground presence, when they are a spell, you have a heal/buff, that does need ground presence. Both kind of defy the usual conventions of the game.

Would it be technically doable to have the offensive usage require ground presence, but the buff/heal usage require none?

Yeah, two of the spell are arcane now. Transcendence change might be good, have not tested it out yet. Spirit Gate being arcane is kinda redundant since u need ground presence but it is still useful to use for your teammate ground unit(arcane).

It will be like life weaving and unholy power, unity, blood thirst, unholy hero, home soil and revenge. I just look up those spell and they are all arcane. Since most of these spell buff your own unit, can Tranquility join them too? Tranquility spell could only benefit flying unit if it changed to arcane.