As for the forms themselves... I had two in mind for the Druid: Wave form and Tree form, invisible on water and in forests respectively. But I'm thinking a Bear form, a Hyena form and a Tortoise form could be interesting.
You can give Tree and Wave forms to druids (btw, I like this idea, very creative
), and leave others with Shur. After all, druids in FFH usually don't have many spells.
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Also, I'm thinking about adding 'global passives' to each Coast (but the Green Sea one) because they're mutually exclusive.
Body units would have a chance to gain a promotion from combat: Adrenaline Rush, giving +1 movement and the possibility to attack multiple times during a turn. There may be a 'neverending effect' to suppress here though.
Nature units perhaps would have a summon perk or bonuses when in forests/jungles.
Sounds good, but spells, passives and global passives might be little too much, at least if you get it at low level. But should work good as a capstone ability, after getting fourth level spell.
Spirit... argh. This one really needs work
For Temperance, if idea of sacrificing something to get something else is viable, maybe something like this(please note, that I have no idea if it's possible to code this way):
1) Meditation: Shur becomes held for 3 turns (casting deley?), after 3 turns he have 50% chance to gain 1-3 xp. This way, you could level you Shur without combat at cost of not using it for other things. Passive effect might give a little magic resistance.
2) Images of Remorse, but I'd give more chance for Guilt promotion and make some chance (like 20% ?) that spell affect Shur that casted this spell. Passive: a little elemental resistance.
3) Shur can cast spell again this turn, but loses ability to cast spells next turn (or even just a good chance to be unable to cast spells next turn ?). Little worse than spellstaff, but it's easier to get L3 shur spells than L3 arcane spells. Passive: gains Spirit Guide for free.
4) Can become 'saint' the way sidar units become shades. Those saints act like great prophet (can join cities, build altar and so on). Passive ability: don't know if necessary, but maybe something like +50% agains disciple units ?
I see them as monks among Ngomele
Unseen Haven is great spell that would fit here, but is a little unbalanced. Not very useful on many maps, but insanly powerful on maps with lots of chockpoints, like Erebus-script maps.
for Spirt:
1) Don't know yet. Maybe something about caliming spirits to remove enraged/mad/crazy promotions ? might also be useful in event 'haunted house'
)
2) Spirt Twisting. A bit complicated, but with good documentation (including chance for broken spirit and ascended spirit) will do. Immunity to fear as a passive ability (you know your spirit from within, so you can't be scared now)
3) We need offensive spell here, to make 'cast again' abilities actually useful. A version of Spirit Twisting that adds harmful promotions to enemies might work. For a passive, maybe increased chance to gain xp via channeling.
4) Reincarnation. Castable only after hero has dies (and would need two versions, as there are two heroes). Creates random Ngomele unit that starts with hero and spellcasting abilities of Banung the Blind or hero and combat abilities of Nga Eye-Eater, depending on version you used. So heroes can get reincarnated as better units, but also as worse. It might be needed to prevent killing and reincarnating heroes until you get good units somehow. For a passive, maybe immunity to broken spirit and mindwrecked, so you can use Spirit Twisting without risk (but still have only 65% chance to get a benefit)
for creation:
I'd use some spells suggested in Re Ki thread. Don't even have to be same spells, as many were suggested