So last night, I got into quite a silly encounter that got me questioning how Guard mitigation interacts.
Pictured below: It was me, 2h Blackguard (BG), a Slayer (SL) a Witch Elf (WE, my guard) and a healing Runepriest (RP) in a conga line back to front in that order, with the WE trying to chase the RP, the SL hitting the WE in the back and me hitting the SL in the back trying to disable/snare him off my guard, to no avail since the WE was permaslowed as well. This went on for quite a few seconds until the WE inevitably died.

Now: What I found strange was that during this chase I took a ton of what I experienced as unmitigable guard damage, to the point where I almost died as well (down to ~25% wounds, which would roughly align with the pure wounds diff between me and the WE (I had low wounds, but very high parry)), until the WE died at which point they went for me and I suddenly had no problem tanking the SL, regen:ing back until a third party arrived and broke the stalemate.
Note: I know for a fact that this has nothing to do with some Rampage interaction since I had it shattered.
Now my guess/question from all of this is: Is the ability to avoid (Block/Parry/whatev) guard damage based on the facing of the guardee rather than the tank? Seems rather dissuading in that case that you can't mitigate incoming guard damage with proper facing the way you can incoming direct damage, and have to rely on your guardee facing the incoming attacks.
More general questions onto that:
How the * does Guard damage even work nowadays? All the resources I've found seem severely outdated and don't correspond to observations. It seems that Parry no longer works for all guard damage and is instead based on whatever the incoming damage type is (which I guess makes sense, but still makes me sad as 2h obv. since investing in any other defence is futile with strikethrough, available gear, and stat dependency). Is this correct? No, it is not apparently How does it work with toughness/resistances/armor? Is it the tank's or the guardee's being calculated, or some mix of the two? Crits - how do they work, is it you or the guardee?
Sorry if I put this in the wrong board