Thanks for the input! I have a few responses regarding some of the points you brought up, and why I choose the options that I choose. I'll try to keep things as organized as I can.

First of all, I'm choosing not to go into too much depth regarding the ins and outs of the support role in this guide. There are lots of guides, videos, podcasts, etc. that go into depth regarding what the support role is, and how it should be played. I'd rather not clutter my individual champion guides with in-depth descriptions of all the roles in the game, and how to play them from a general perspective. In summary though, I believe the role of a support is to do as much for the team with as few resources as possible, and to a lesser extent, to help control the lower half of the map, and protect the duo-lane carry during their weaker early levels.

In regards to linking masteries, items, champion names, and so forth, simply surround the words with two sets of square brackets.

Regarding Jarvan IV's role as a support, I disagree with your claim that he is best played as a kill-support and lane bully. He can definitely fill this role into certain matchups, and if you capitalize on enemy misplays, but as a melee support, he already has a disadvantage in the early laning phase, most of the time. Once he has a few levels, and the map begins to open up, I believe Jarvan IV starts to really shine. His mobility and catching power become a huge asset, but as a support, he shouldn't usually be strong enough to fight the enemy team 1 on 1. He's much better off making roaming plays around the other players in the game, or protecting carries.

Regarding masteries:
Grasp of the Undying is fine, but not great. As a benchmark, say we have Sightstone and a few levels, putting us at 1000 health. When you engage, you'll proc it once, maybe twice a fight. That's 30-60 magic damage, and 15-30 health back. After taking magic resistance into account, that'll probably be around 21-42 bonus damage. At 1000 health, Stoneborn Pact provides an extra 50 health, which is certainly less valuable than Grasp of the Undying on it's own, but it also provides your carry with an additional 15 health per second for the entire fight. In my opinion, this is far more valuable. The more survivable your carry is, the more aggressively they can play, and the more you two can bully.

If you really want to deal damage on your own instead, I'd recommend a different rune set-up, with different item priorities, leaning more towards budget damage and assassination. You'd probably look to use Fervor of Battle for this, or possibly Thunderlord's Decree . It's a high risk, high reward playstyle, but can work against you if you don't snowball pretty hard.
( Fervor of Battle can still kinda work with a tanky build though)

Fearless largely applies to 'bonus' resistances, which you have nearly none of early, and enough to gain maybe 20 armor and 10 magic resistance from on 6 items (as a support), although there is some value in it against burst damage. The problem there is most of the trades in bot lane that matter aren't burst trades, they're somewhat drawn out, and the bonus resistances aren't nearly as valuable. Insight , however, gives you more frequent power-play opportunities with faster cooldowns on Exhaust or Ignite, and more safety and play-making potential with reduced Flash cooldown. Furthermore, later in the game, it's even more valuable. Having Exhaust up 15% faster can be the difference between protecting your carry from an assassin, and winning the fight (and possibly game), and not being able to, and subsequently losing.

Regarding Courage of the Colossus , I do talk about this in the guide, and definitely think it's a very strong option. If you're the initiation for your team, it's 100% the way to go. I should probably add that if you're laning with an AD caster rather than an auto-attack based carry, it's also easily the best option.

Regarding lane synergies, believe Jarvan IV works pretty well with all of the carries right now. For the bully carries like Draven and Lucian, he can play aggressively, and set them up to bully without taking heat. For the scaling carries like Twitch and Kog'Maw, or the opportunistic carries like Ezreal and Vayne, he has the flexibility to pick and choose fights without being forced to commit to fights, unlike someone like Leona. Similar to Leona, however, he stays relevant even if he only builds tank stats, due to his built-in utility.

You are correct though, he's definitely not an ideal pick into Thresh and Alistar, if you're trying to play aggressively. If you're playing defensively, however, he's fine into these match-ups. I think anything that typically counters melee supports, such as Caitlyn will be difficult for him, although he has the engage range to lock her up for gank set-up. Lucian and Ezreal are difficult in the sense that they're difficult to hit with your E+Q combo, so if you're playing aggressively into them, you're forced to engage on the support if they have their dashes up. If you're against something like Lucian + Thresh, you're kinda forced into playing counter-agro. There's nothing wrong with this though, and Jarvan IV scales well into late game any way. A good Vayne is probably the hardest to deal with as she can Condemn you out of your gap closers, Tumble out of them, win in drawn out engagements against most melee + ADC lanes, and scales well.

I don't agree with Frozen Heart rush at all for Jarvan IV support, or any support for that matter. Sure, it gives a lot of armor and CDR (and mana, but that's basically irrelevant), but it will leave you with an incredibly small health pool mid-game, meaning that despite your armor, your effective health will be fairly low still. On top of that, many if not most of the supports in the meta deal significant magic damage (as well as many of the mid laners and some of the junglers -- and you'll be encountering them at this point). These magic damage threats will burn through your tiny health pool incredibly quickly. Not only that, but you're delaying your first item power spike. Redemption is incredibly cheap for the effective scrapping potential it provides. It gives 300 health and 10% CDR (not to mention sustain stats while you're roaming, as well as a tiny buff to your W), and provides somewhere around 200-300 AoE healing, as well as the threat of 10% max health true damage in fights and scraps. For perspective, let's look at a level 9 3v3 scrap. The enemy champions will have somewhere between 1200 and 1800 health on average, probably. We'll use 1500 for simplicity. That's a potential for 265*3 (795) health in healing and 150*3 (450) true damage. That's essentially 300+795+450 (1545) health worth of fight-relevant stats on a fairly average fight. For 2100 gold. And it only scales up as you group.

As I mention in the guide, I'd only recommend building Frozen Heart if you have your core items done, have a significant health pool already, need armor, and are facing against an attack speed heavy team comp.

I agree with you, Jarvan IV is a very good engager and catch champion. As a support, he's particularly good at catching people out.

Regarding runes, I have my preferences listed in the cheat-sheet at the top of the guide. If you mouse over the 'notes' tab, I've listed a few other options that I could see arguments for. I might expand on this in the future, in it's own guide section, but for now, if you're interested in my logic behind the rune choices, I'd be happy to go into that.

Thanks again,
-C.

Yeah yeah, getting around to it.
Thanks!