Class/Job "Sub job system"

[Ashkendor]

Example of what should be allowed on THM sub:
Fire(would be interesting to get astral fire/umbral ice @ 1 stack on other jobs)
Fire II
Blizzard
Sleep
Lethargy
Aetherial Manipulation(This could be nice on some melee jobs)

Allowing a stack of Umbral Ice for anyone that uses mana would be utterly broken. Current MP recovery skills would suddenly be useless if you could just cast a Blizzard spell and get that massive mana regeneration from Umbral Ice. Shroud of Saints on cd? No problem, just have your WHM throw out a Blizzard spell. If I could cross-class it on PLD, I could probably spam Clemency pretty effectively. SMN wouldn't have to worry at all about mana conservation. It works on BLM because they're built around it, but it breaks everything else.

Example of what should be allowed on ACN sub:
Bio
Aetherflow(1 Stack max, would love to have this on DRK)
Energy Drain
Bane

Bane would be useless because it only spreads Bio, Bio II, and Miasma.