Hi!
Pretty interesting, but I have a few questions about runes
I cannot understand the secondary rune choise
You're picking free boots and approach velocity, but, as I can see, your playstyle is about ultimates and passive laning
So why don't you pick Ultimate Hunter from domination to have even more ults. Also, domination tree has cheap shot (that procs from Q and E) and zombie ward (which is good for vision control, as you're still a support) or even ghost poro (for the same reason as zombies)
Also, you are going to get your boots pretty late in the game (because you are playing passive according to your own words, and their "spawn time" lowers with kills), but as a support you want to roam at least a bit, and boots help with it, so getting them early is important, but you cannot (because of your rune choise). So, if you want to have more gold, why not to go Future's Market (50g fee seems to be not that big, but I can be wrong with it, because I use inspiration only for early sustain with biscuits)?
Also I don't feel like Shen needs approach velocity. I understand it's synergy with Frostfire, but do you really need that bit of movespeed if you already slow them? Isn't Cosmic Insight better in that row (flash on supports like Shen is important, so having it more often is very good)?
I might be wrong with all of it, as I am not playing Shen often (but as an ADC main still love having him in my team)
Still thank you for the guide