Season 5 {Divine uprising} Ymir Tanky support build!

Sovereignty still holds up better throughout the entire build, whereas Jade Emperor's Crown sort of falls off late-game.

Sov's 15 phys prot aura is good enough to cancel out the pen from any one flat pen item, and the HP5 is always helpful. Agreed that Stone of Gaia isn't as good...the HP5 got nerfed noticeably, and is absolutely situational with the passive. The HP5 is still strongest of all items, and the 400 health really is nice...but...well, I'd still consider more counter items. Qwacky does list Witchblade as an option, but Midgardian Mail should be another.

Gauntlet of Thebes is perhaps situational, and depending on build order, I might consider it as a late option in place of Stone of Gaia. Thing is, if going aggressive, Gauntlet really isn't a perfect fit. To get any protections out of it, you need stacks.

If facing more physical threats, I'd possibly even fit Sovereignty 2nd...and then follow up with either Void Stone (aggressive, almost deal true damage to squishies) or Genji's Guard (great all-around stats and amazing MP5) depending on my intent.

Here would be my main build cores...and if playing Conquest as Support, would add Guardian's Blessing as a starter.

• Aggressive vs more magical: Shoes of the Magi, Void Stone, Breastplate of Valor, Gauntlet of Thebes. (Void 2nd is great for aggression, and BoV immediately after is for the CDR. Thebes at the 4th spot is a bit late, but should stack easily, and is okay without stacks at this point because you've already built physical and magical protections.)
  
  
• Aggressive vs more physical: Shoes of the Magi, Sovereignty, Void Stone, Breastplate of Valor. (Sov 2nd allows you to soak up damage from the physical gods, while providing some health and HP5. Since it's more of a true defense item, rush VS next for that protection reduction. BoV after for the CDR.)

In any case, I would consider Void Stone more of a core item when going aggressive (as is indicated by going with Shoes of the Magi). I also would be unlikely to get Mantle of Discord, personally. People usually try to get AWAY from Ymir (re: ult and freeze), so it's often unlikely he'll get much out of the passive. Instead of Discord, I'd probably slot in a more standard counter item, though it's okay to throw in there as a stock build example.

And where is Blink Rune as a relic option, anyway? If going aggressive, it's absolutely a consideration. Not core anymore, due to the CD nerf, but still a valid option.

I'd swap 'em out for either Shoes of Focus or another MS item lategame, but Ymir can make good use of them early.

Yes.

Shoes of the Magi (or other shoes), Gauntlet of Thebes, Breastplate of Valor, Pestilence (or Bulwark or shogun's or genji's) Emperor's Armor (or Midgardian Mail), Mantle of Discord.