Best IV for Tiki? +Atk, +Def, or +Res

Mixed tank, physical tank, or magic tank?

I personally wouldn't go +Atk since +Res/Def will help her tank more and help her survive attacks if going for breath + Aether combo.

Before steady stance 4 I would easily have gone for +atk. The guard + QR combo is only available to one character at a time (unless one skill or the other is on their weapon) and there's always a use for the QR seal so I try to keep it free. (Also, I was never a fan of QR tanks because once your QR is down you're kind of a sitting duck.) Which means I liked the idea of OHKO on A.Tiki, which meant +atk with the prf and skills like death blow, brazens, vantage, maybe DC, special spiral, glimmer, you get the picture.

Now that steady stance 4 is a thing, I'm open to +def and +res again. +def can get insanely tanky with steady stance 4 and Breath of Fog, like, 50 def is not even that hard. So she can take two hits and brazens might not even activate. +res I have a hard time understanding...how do you get her res high enough to take two hits and not have like 2HP left?

You have the three best IVs, and though I've been building Tiki forever, I am still stuck with this conundrum too. What I've been told, and I think it is true, is that "+Atk is marginally better than the +Def in neutral match ups, but the +Def in conjunction with Bonfire or Ignis will be able to tank and defy many disadvantageous match ups."

With having Tiki as an Anti-Dragon/mage, her res isn't so low that she can't tank even one hit from other dragons, excluding other Tikis with dragon-effective weapons. So even unboosted, her res/hp should be plenty good to tank dragons for one hit, and one-shot in return with her prf weapon. As for other Tikis, just initiate on them first instead. Same for mages - boost her attack high enough, and what is really going to survive one hit from a ~70 atk Tiki hitting on their lower defensive stat? (prf weapon, +atk iv, something like atk/def bond SS and whatever buffs from her team).

There's just about as good an argument to be made for +Def, since she can wall physical threats even better and perform her other functions well too. I think that +Atk or +Def are your best bets, and play to her strengths. BUT! If you want her to be a dedicated res tank, tanking multiple hits from mages and the like, it can be done...but she will always be a mix tank. her res is naturally so low and her def so high that she will naturally be bulky in def regardless. with +Res, warding breath, lightning breath res refine (which I would recommend instead of her prf if you want to tank res repeatedly, because she'll gain more res from the refine and the free A-slot where DC would have been with her prf) and something like distant defense SS she hits something like 41 res, 45 after +10 merges. Which is good, but why not build a Fae to tank mages and other dragons repeatedly if thats the role you need filled? Fae is able to reach much higher res than Tiki and can fulfill this role much better. If it's because of dragon-effective green mages, I think you'll find, as I have, that Tiki can tank one hit and KO in return, almost always. only in ideal conditions is she being 1-shotted by them, and this becomes less and less possible as tiki accrues merges. (bulkiness increases more than attack with merges, i.e. +4hp and +4res, but only +4atk)

I wouldn't sacrifice your Dorcas for her. I'd probably keep all three IVs until you decide what you want to do with her, since merging such great ivs seems a real shame, and copies of her without perfect ivs will surely come to you in time. So yeah, I'd recommend +atk or +def, but I'd keep all those IV copies.

This is a build i recommend to be able to kill and tank in the same time, if you cant trigger bond or don't have DC you can use LB+ and brazen atk/def to have similar results.

I had +Def -Spd for a while. Wished she had more speed to actually dodge some doubles. Also wished she had more attack to cleanly kill off her opponents. That led me to switch mine to +Atk -HP. This is just anecdotal though. I run Fog of Breath and DC on her, together with a +Spd Nowi and +Spd F!Grima.

+Def -Speed.
With 52 def when attacked she is a unbreakable physical wall who saved my ass many times.