Or, how I went full circle. This was sort of born off some random ideas I had after reading a thread about wanting a caster tank. I originally wanted to make it an anti-mage class like the Dragon Age templars but the idea took a life of its own.

Mystic Knight

Weapon: Mace/Club & Small Shield/Buckler.
Cross Class: GLA (Provoke, Convalescence, Flash), PGL (Second Wind, Featherfoot, Internal Release)
Main stat: INT
Equipment: Caster gear; basically anything THM, ACN, BLM and SMN can equip pre-50. Once they hit post-50 their gear would have the "of Warding" suffix.

Mechanics: Mystic Knights are tanks that fortify their defenses through magic and aether. Aside from increasing the hardiness of their equipment, they can manipulate aether to further strengthen themselves or punish enemies as they see fit. They do this by marking enemies with aether signatures, which can then be manipulated in different ways.

Abilities
01 Double Beat - Delivers an attack with a potency of 140.
02 Wall - Increases your Defense and Magic Defense by 15%. Duration: 20s. Cooldown: 60s.
04 Skullbreaker - Delivers an attack with a potency of 100. Combo action: Double Beat. Combo potency: 160. Combo bonus: Increased enmity.
06 Infusion - Your weaponskills consume MP to deal additional unaspected damage with a potency of 70. Duration: 20s. Cooldown: 90s.
08 Shining Strike - Deals unaspected damage with a potency of 100. Combo action: Double Beat. Combo potency: 170. Combo bonus: Restores MP.
10 Mystic Armor - Increases enmity and the defense gained from armor and accessories. Switches skill speed and spell speed values. Effect ends upon reuse.
12 Flash Nova - Consumes MP. Deals unaspected damage with a potency of 100 to nearby enemies. Additional effect: Increased enmity.
15 Seraph Strike - Consumes MP. Delivers an attack with a potency of 130. Range: 15y. Additional effect: Increased enmity.
18 Brainshaker - Delivers an attack with a potency of 100. Additional effect: Stun for 5s. Cooldown: 40s.
22 Sunburst - Consumes MP. Deals damage over time with a potency of 40 for 24s. Additional effect: Places a Solar Mark on target for 24s. Overwrites Starfire. Can only be active on one target.
26 Hexa Strike - Delivers an attack with a potency of 100. Combo action: Shining Strike. Combo potency: 260. Combo bonus: Increased enmity.
30 Runic Weapon - Increases damage dealt by 10% and removes "increased enmity" effects from all attacks. Adds a cast time of 2.5s to certain attacks. Effect ends upon reuse.
34 Shield Barrier - Reduces damage taken from the front by 20%. Reduces damage taken from the flanks by 15%. Reduces damage taken from the rear by 15%. Duration: 10s. Cooldown. 90s.
38 Vidohunir - Consumes MP. Deals unaspected damage with a potency of 100. Combo action: Skullbreaker. Combo potency: 250. Combo bonus: Increases damage dealt from your magical attacks by 10% for 24s.
42 Starfire - Consumes MP. Deals damage over time with a potency of 40 for 24s. Additional effect: Places a Stellar Mark on target for 24s. Overwrites Sunburst. Can only be active on one target.
46 Black Halo - Consumes MP. Deals unaspected damage with a potency of 40 to nearby enemies. Additional effect: Damage over time with a potency of 30 for 24s.
50 Randgrith - Consumes MP. Deals unaspected damage with a potency of 100. Combo action: Shining Strike. Combo potency: 240. Combo bonus: Reduces target's resistance to blunt damage by 10% for 30s.

Traits
08 Enhanced Vitality
14 Enhanced Wall - Increases Defense and Magic Defense gained from Wall to 25%.
16 Enhanced Vitality II
20 Mystic Defense - Activating Mystic Armor also increases your shield's block value.
24 Enhanced Vitality III
28 Enhanced Brainshaker - Reduces the cooldown of Brainshaker to 20s.
32 Magic Bulwark - You are able to block magic spells when Mystic Armor is active.
36 Mana Flows - Increases the amount of MP recovered per tick while in combat.
40 Hasty Infusion - Reduces the cooldown of Infuse to 60s.
44 Critical Blocking - Your blocks can now be critical, blocking 25% more damage.
48 Enhanced Shield Barrier - Shield Barrier now makes all your blocks critical for its duration.

Job Abilities
30 Shield Blast - Consumes MP. Deals unaspected damage with a potency of 130. Range: 15y. Can only be used after a block. Requires Mystic Armor. Cooldown: 15s.
35 Aetheric Collapse - Deals damage over time with a potency of 100 for 9s. Can only be used on targets below 20% HP. Cooldown: 60s.
40 Spirit Taker - Deals unaspected damage with a potency of 200. Cooldown: 30s.
----------Solar Mark: Restores HP equal to 100% of damage dealt. Consumes Solar Mark.
----------Stellar Mark: Creates a damage absorption barrier that negates damage equal to 10% of your max HP. Consumes Stellar Mark.
45 Mute - Interrupts and prevents spellcasting for 2s. Cooldown: 45s.
50 Magic Barrier - Reduces most damage taken by 90% for 10s. Cooldown: 300s.
52 Judgement - Deals unaspected damage with a potency of 200. Cooldown: 30s.
----------Solar Mark - Reduces target's physical damage by 5% for 10s. Consumes Solar Mark.
----------Stellar Mark - Reduces target's magical damage dealt to you by 5% for 10s. Consumes Stellar Mark.
54 Runic Circle - Creates a designated area at your feet that reduces physical damage taken by 10% and magical damage taken by 20% for party members who enter. Duration: 10s. Cooldown: 150s.
56 Mana Bomb - Consumes mark on target, dealing unaspected damage with a potency of 200 to target and nearby enemies. Cooldown: 60s.
58 Shattersoul - Consumes MP. Deals unaspected damage with a potency of 100. Requires Runic Weapon. Combo action: Skullbreaker. Combo potency: 300.
60 Exudation - Deals unaspected damage with a potency of 150. Cooldown: 45s.
----------Solar Mark: Increase potency to 300. Consumes Solar Mark.
----------Stellar Mark: Restores 30% of your current MP .Consumes Stellar Mark.

About Mystic Armor
Mystic Armor is your defensive mode. Because MTK is limited to caster gear, this stance does several things. Upon activation, your gear's defense rating is bumped up to match that piece's magic defense. So on a cotton robe with 15 defense and 31 magic defense, activating Mystic Armor will increase the robe's defense to 31. While not mentioned in the description, Mystic Armor would then multiply the resulting Defense and Magic Defense times 1.5 and use the result as your Defense/M.Defense values.

Secondly, it converts all spell speed on any equipment to skill speed. This is to facilitate tanking given the gear selection the job has.

Thirdly, (via the Mystic Defense trait) it increases your block value. By this, I mean that the bucklers and small shields MTK is limited to will be able to block more damage while Mystic Armor is activated. The plan here is that a small shield/buckler would be able to block as well as a kite shield while keeping its higher block rate. The Magic Bulwark trait plays into this because after lv32 you'll be able to block damage from magic spells.

About Runic Weapon
I'm sure people will say "Duelle, you hate Wanderer's Minuet, so why'd you slap it on MTK?". The way I look at it, the DPS mode for MTK should be a caster. The 10% damage increase is a placeholder and can be bumped up, but the idea is that it'd have to spend time channeling magic into their mace/scepter before releasing. There should be a jump in damage potential once you switch into DPS mode, and what comes with that to keep it balanced is casting times.

Also keep in mind that by switching into Runic Weapon, you're losing all your defense and M.defense bonuses and become as squishy as any caster (specially since MTK gear would be itemized close to "of casting" gear). By the same token, all that spell speed on your gear would be put to use while in this mode as well.

The skills that receive a cast time are: Flash Nova, Seraph Strike, Black Halo, Vidohunir, Randgrith and Shattersoul.

Notes
- All MTK skills scale with INT.
- The aesthetic for this should really be something along the lines of the healer soldiery set (which had armored gloves and boots).
- The mace skill names have all been lifted from FFXI.
- MTK has only one purely physical combo, being Double Beat => Skullcrusher => Hexa Strike.
- MTK without stances activated has no cast times. It's "magic" mace skills still consume MP.
- Mitigation comes via Wall (increase def and M.def), Shield Barrier (damage reduction), Spirit Taker, Judgement and Runic Circle.
- The idea behind the design is that MTK would have inferior HP scaling to PLD and DRK but higher defense values to sort of compensate. The numbers might need to be tweaked but the goal is for it to have equal EHP to the other tanks.
- To give you an idea of the thought process for the abilities that consume marks, picture them working like this, but with particle effects.
- Graphically, Mystic Armor should make your buckler/small shield radiate an energy field to make the area blocked by the shield bigger. Sort of like this.
- Mana Bomb is sort of iffy in this design, since I originally wanted it to work like Living Bomb but that ended up clashing with the mark system in place.
- I really wanted more abilities like Shield Blast, but that became more of a chore to design than anything else so it's sort of limited to that. Suggestions on that topic are welcome.