ARGUS TANK NOW! Support

The problem is experienced supports aren't really killing enough minions to fully stack Book of Thoth + getting enough assist stacks to fully stack Thebes in time. Respectfully speaking I really don't know what games you are playing to ever be able to stack both of those while still being relevant and not stealing/leeching too much farm. I also don't know how you survive with so little defense, it's like you are dependent on getting under 40% hp for the Book of the Dead + Bulwark of Hope shields which is cool at first... but once the shields go away you are still under 40% hp with very little hp5 and no lifesteal, so you have to go to base regardless.

Also, the build is pretty expensive with no team auras outside of Thebes and very little defense. You can't tank very much without your 3 or the shields you get from being very low, you also don't do any damage to tanks because you have no % pen and do insignificant damage to squishies because you have no flat pen; you have a good amount of power but nothing to go with it. This is ignoring the fact that you should not be building so many power items as a support... if you're gonna build power items, at least get some flat pen so that you can do something with that power

You're also getting Mystical late, which is REALLY late for a support especially in this meta where supports are still level 17 30 minutes in, and it's essentially useless at that point + not really built on supports regardless.

I get the whole thought process behind the build - you want constant shields so you can't really die. The problem is it's a very selfish, expensive, and stack-dependent build with no real utility/auras for your team - if I ran this build anywhere it would be in solo and even then I would change a lot.

Also you said something about the starter item, but I'm not sure - do you just build Sentinel's Gift for the early gold/xp and then sell it late? Because you have 6 full items late game and no Sentinel's Embrace

ANYWAYS My suggestion for a shield-based build that actually supports the team is the following!:

Sentinel's Embrace > Gauntlet of Thebes > Sovereignty > Bulwark of Hope > Pridwen > Mantle of Discord

for a build with more damage I would just swap Sovereignty for Spear of Desolation or Divine Ruin

Isn't it obvious? Kill the melee minions and just assist on the archers! XD

Yeah, BotD + BoT are NOT suggested items for Hera, esp in a tank build.