It's not Tank Meta, it's Faf Meta (Patch 10.6)

Sentinel's Embrace is the safe, go-to starter upgrade. It will make you and your team even tankier, enough said. Sentinel's Boon's stats are very good and is the more selfish option, but I think the passive is not good enough for the selfishness to be worth it. I haven't tried much War Flag, but apparently might be viable or even meta this patch. If you use it, always go with War Banner as the upgrade; the other one is laughably bad. As for the Benevolence tree, I love Benevolence as a starter and both upgrades are strong. But one thing that prevents me from using it on Fafnir is its lack of protections. Especially since both upgrades, with my standard build, will prevent you from reaching the 600 prots threshold for cloak's passive.

After all protections on items got nerfed in 10.6, it's really hard to make the most of Prophetic Cloak's passive on most gods. That being said, Fafnir is one of the few that Prophetic is still great on. With his passive giving 35 of each protections (which can exceed the 325 prot cap) when above 1000 gold in hand, he can still pretty comfortably hit 600 total protections with just 5 defensive items. Without taking 3k pots into consideration it's actually still possible to reach 600 with just 4 items, allowing 2 damage items in your build. But I wouldn't call that sort of build optimal.

A crazy thing about Pridwen on Fafnir, now that his ult got buffed from a max duration of 40s to 60s: your dragon form will now outlast Pridwen's internal cooldown once you put a 4th point into it. Yes, late game you can proc Pridwin twice per ult usage, both on transformation and de-transformation. Pick either glyph depending on how the match is going, whether you want the double-double explosion or the double-double shield. You can't go wrong with either, but I think I slightly prefer the larger shield of Reverent Pridwen as it can help survive those dicey de-transformations that often result in CC-chain hell.

We all know about Stone of Binding and its ability to boost your (and your team's) damage greatly via protections shred, while also piling on tankiness. No need to go much into it here, other than to note that your 1 and your 3 proc it in both dwarf and dragon form.

I was always a fan of Manticore's Spikes on Faf, and now its passive got a buff this patch. Both his 1 and 3 will drop spikes, and all your abilities (even if you use the 2 on an ally) will proc the bonus damage. What's more: during your ult, since your abilities turn into DoT damage, you can get a spike AND proc the bonus damage with one ability. This item makes your ult way deadlier to squishies than it already was.

Ethereal Staff is another pretty strong power item that both mages and bruisers seem to like this patch so far. It was a decent (if a bit underrated) bruiser item before, and now its % HP proc got a small buff making it a bit more desirable to anyone that can buy it. Manticore's Spikes also synergizes super well with E-Staff since Spikes scales off your max HP, including your currently stolen HP. In addition, this is the only item in this build that provides CCR and most games you will need it, especially when you get focused in dragon form. And even more health as a little bonus because why not. I like to buy it early since that's when the power it provides is the most impactful. The early protections you're sacrificing isn't felt as much when you combine e-staff's utility with Faf's passive.

The relics included are just what I like using on him, go with whatever fits your playstyle/team comps.

Note that I'm mostly a casual player and that this build guide was made with no particular game mode in mind, but I pay close attention to the meta in ranked and competitive, and took that into great consideration here as well.

No. More. Short jokes.