Here's one that I've been thinking about
Job: Time Mage
Branching Class: Thaumaturge
Secondary Class: Arcanist
3rd Class for skill pulls: Conjurer
Role: DPS
Time mages could be similar to how bards work, which is being able to use support abilities and do damage. Kind of like the magical version of Bards, but with some very unique spells such as trademark haste and slow.
Thaumaturge is the branching class because it fits in with previous ff games. Supporting abilities such as slow and haste are kind of linked in with thaumaturges as well, and Arcanist because it's based heavily around status effects. It would also give some pretty cool spells like virus and eye for an eye.
Possible Skills: Along with some fan serviced spells, I've thought of a few that could be quite cool to use.
I'm gonna use Uberhaxed's template.
Haste - Increase spell and skill speed of a selected friendly target by 20% for 15 seconds. 60 second cooldown. I really think Hastega would just be completely overpowered, that's why haste is used as one of the job skills. I think giving the signature ability Haste as the very first skill would really motivate people to continue levelling the job.
Slow - Decrease spell/skill speed of a targeted enemy by 20% for 15 seconds. 60 second cooldown. Pretty much an inverted haste.
Meteor - Deals a 600 potency aoe with a cast time of 6 seconds that costs all of your mana, you are also unable to enter umbral ice for 5 seconds,. It's kind of like a watered down version of the caster's lb3. The huge cast time really highlights how this is the most damaging spell time mages have. Which is really emphasised in previous ff games.
Doomsday Clock - Everyone in the party receives a buff that increases the potency of their attacks by 15%. This lasts for 15 seconds and after the duration everyone receives a debuff that lowers all damage dealt by 25% for 15seconds. This encourages some thinking on when to use this spell. Even though it lowers overall dps, I think it would be quite good on dps checks. 2 minute cooldown with a 3 second cast time.
Time Collapse - All damage dealt in the past 3 seconds will be dealt to the targeted enemy. Single Target spell with an instant cast time and a 1 minute cooldown. Limit breaks don't contribute to this. I think this would really encourage co ordination and timing of attacks. Like using this skill right after a black mage uses flare.
Ofcourse, for balancing purposes, the time mage job crystal wouldn't give nearly as much intelligence as the black mage job crystal. It'll probably give no intelligence points at all, but could put some points into piety.