
Originally Posted by
Tashan
For tanking you generally want to have an Evasion build. Disagreeing with posts made by Kwate and Scuro, the job has access to more than enough Evasion to be able to tank anything a MNK, NIN, THF or DNC would.
The difference between those jobs and Blue Mage is the requirement of equipment. Those jobs have enough natural Evasion to get the job done and can fortunantely stick with their Haste TP builds to do so.
With full merits and capped skill, a Blue Mage typically needs roughly 65 extra straight evasion to tank comfortably. With Gnarled Horn Atma, you need roughly about 40 more. I typically also try to use pieces with Subtle Blow on. It is possible to cap Subtle Blow with sets such as the Alcide's Harness, Heed Ring, Rajas Ring and augment Gules Harness pieces.
I personally like to keep a Full Evasion set also just to fall back on for things such as Ichi casting, but many don't find it neccessary.
Your support job options are /MNK or /NIN. /MNK is for Counter/Eva tanking and /NIN is for Blink Tanking. If you go with /MNK you need to use Gnarled Horn and Atma of Roaring Laughter to cap Counter with Counterstance up. You also need to cap Accuracy for the best success of landing the counter hit. If you go with /NIN you'll want to keep a Fast Cast/Haste Gear set for your shadows. Occulation works well, but if you're fighting a monster with single target nukes you'll want to use Utsusemi more often.
For meat tanking you want to stick with the tried and true defense increase with Cocoon and Taco. Other than that you want to get as much Physical Damage Taken%- equipment as you can. Some notable peices are Shamashir+2 (Earth path), Genbu's Shield, Augmented Dark Rings from [A] Konschtat, Cheviot/Umbra Cape, the Darksteel Harness Set, Twilight Torque, Denali Mittens, Louhi's Mask and the "A Shantotto Ascension" leg armor with the augments.
As for spells, Actnic Burst, Temporal Shit and Head Butt (if effective) are staples. The Evasion Bonus trait is helpful, as can be Occulation. Auroral Drape's Blind/Silence is good if it is effective. But otherwise you just want to deal as much damage as you can to keep hate coming your way. Also, don't ignore the Flat Blade. I find it to be the best, fastest and most reliable stun in most situations.
As advice from experience please leave your Haste, Refresh and Erase to your support if possible. The worst thing I find that happens to me is when some big TP move/Spell is coming and I can't either cast shadows/stun in time because I'm in the middle of a casting animation.