Yes, and no. Renekton has one stun, on his W. Other than that, he's basically LoL's tankiest assassin (no matter what RIOT wants to call him). Renekton excels at gap closing to a squishy target, then one-banging them off the map almost instantly. He is quick around the map, as he can dash through most walls with E. These traits make him an assassin, regardless of whether he is also other things.

Renekton is also a tank killer. He has the stats and kit to bring down tough champions. W is his meal ticket there; it busts shields when empowered, and it is an auto-attack reset that is also two attacks (perfect for proc'ing Blade of the Ruined King). He's one of the few melee champions, pretty much the only one, who trounces Sett so badly that it's not even close.

You know where you find plenty of squishies AND tanks conveniently located in the same place for double the murder rate? In the bot-lane. Renekton, like in every other position you want to play him, will do fine and kill whoever is against him without that much trouble.

But I don't want to mislead anyone. Renekton doesn't just rake in assist gold. He gets kills, sometimes solo kills, even as "support". What he does is protect your ADC well. They can't kill your ADC if they are already dead. This frees your ADC to get tower plates with ease, to roam mid and pick up a kill/assist, to help get dragons, etc etc. If you have an ADC that doesn't need as much babysitting, like a W-max Tristana that just needs some starting gold to get rolling, then Renekton can be an excellent choice. But I find that he is strong enough to support any ADC. You just have to take better care of some than others.

First, let's talk what "support" really is. Support as a role exists due to a gold shortage imposed into the game. One player gets the gold from farming each lane, one player gets to farm the jungle camps, and one player... is screwed. Thankfully RIOT gives supports gold-generation items, so that they get to have items too as the game progresses. Outside of how support gets gold... support is whatever you want it to be. You do SOMETIMES have one job; keep your ADC/APC alive if you can and help them get enough gold to start snowballing. Some champions don't even need that help, and it's not always the best use of the support position to try even when they do need it. Games are not always won and lost on how well your team's ADC does.

Renekton excels mainly at one thing; being a killer even if he's behind. You don't need to be fed to jump someone and nuke them with Renekton, and if your stun is empowered there's very little most targets can even do about it. He's going to be useful in every aspect of the game. He is good at killing towers and objectives; for example he able to solo dragon at level 6 without a jungle item or Smite. He has cc that eventually gets to be on a 5.4s cooldown, can kill anyone in the game with at least fair chances, is fast around the map, etc etc etc. The only thing he doesn't do is shoot stuff, though technically he launches himself pretty dang far as a living silver bullet.

What Renekton support is for is to have a fully combat-capable fifth champion on the map. You don't need to buy "support items" on him and pretend you are Dr Renekton. You just get Spectral Sickle which says your gold is inside the enemy champions in your lane, ruthlessly extract said gold with your trusty weapon, and watch as your KDA (and that of your ADC) goes up up up.

HEALING UP BETWEEN ENGAGES
There is not that much different about playing Renekton as support, except that you have not as much reason to max Q. You aren't taking the minions, and Q's cooldown doesn't go down with ranks. You have to heal up in other ways.

The first way, and one that Renekton players don't often make proper use of because they don't use Ultimate Hunter or rush-build their CDR, is using R just to heal. You get quite a huge chunk of health from it, which you get to keep when the ult ends. There is not a whole lot of difference between getting that health during combat and getting in the form of healing -- you mainly only miss out on the damage aura, which while a lot of damage isn't remotely needed to kill someone (especially a squishy).

The second way is all the lifesteal that you build. This is better for healing up than Q, because it minimizes the number of minions you might kill. You can actually heal as you kill zero minions; just get them low for your ADC to finish off. Q, as long as you don't have so many ranks in it that you are one-shotting minions, can augment this a little but isn't really necessary.

The third way is to pop into the jungle and take a camp. Once you have a strong lifesteal item, Renekton will heal up as he grabs some extra gold. You only want to take camps that your jungler doesn't bother with; don't disrupt their path. It is pretty common for blue-side junglers to leave the krugs for the ADC/support, as a source of extra gold for that lane. It's a hard camp for some junglers to take quickly at lower levels, and it's a bit out of their way unless they are coming to gank bot-lane and will need to wait 10-20s before the situation there will be good for the gank. From red-side, you can take the Gromp which is not that huge of a blow to your jungler by the time you have your lifesteal item anyway.

WHEN TO TOWER DIVE
Don't do it. Just... don't. There definitely are moments when you will get away with it. But most of the time, you take more damage than you deal. Most of the time, you will die rather than get the kill. The only time tower diving works is when you are a far better player than your target -- and if that's the case you'll trounce them anyway without needing to take risks.

Once you have a habit of noping out of the tower-dive option, that's when you can start considering the tower-dive again. It's almost always the wrong play. For every tower-dive that goes well, three or four of them are a disaster. You have to stop going in to find out, and learn to see whether the dive will 100% work BEFORE you commit to it. At the point where you can tell, you can ignore this advice. You won't need it anymore.

I will also say there's an exception to the "no tower-dive" rule of thumb. If your ADC goes in... unless they are full-on int'ing then you need to go in too. Make sure that your E is available to get you out from under the tower. If you dash in, dash in as late as possible (with Slice) so that your second E (Dice) is up for longer. If you haven't gotten out by the time Dice is lost to you, you stayed too long. Your job isn't to tank for the ADC; they made their call and if they die they die. Your job when going in is just to make sure that the play is at least a 1 for 1, rather than your ADC feeding a free kill for nothing.

WHEN TO ROAM
Since you want to stack Ultimate Hunter so that you can rapidly heal up more often (or actually use your ult the intended way *gasp* more often), some roaming with Renekton is advised even at low levels. You don't need to go back up your lane after recalling. Roam mid, get a kill/assist there, then go to lane via the river. You might even pick off the enemy jungler too, if they are dumb enough to try and come help mid. You can get 4 of your 5 Ultimate Hunter stacks pretty easily this way.

Getting the enemy top-laner is a bit more difficult. It's out of your way, so typically you won't roam here until you get your first and maybe second bot-lane tower down. At this point your ADC should be going mid, where it is safer for them to be, so that your team's split-pushers (of which you can be one; the moment you sell your support item) can start doing their thing. Whether or not your ADC goes mid is irrelevant; if they do you can get back to them after ganking top, and if they don't then they are either so fed they are fine or don't know how to ADC and are therefore dead weight (either way you should stop babysitting at that point; here is where you can consider selling your support item to start raking in farm gold).

Renekton has become one of my favorite alt-picks for support role as of late, when Yuumi isn't available. (I also like support Zilean and my own brand of Soraka; build guides for both are coming soon.) Until I had my Yuumi's build down, she was actually the alt-pick for him actually. It has been impossible to put him down. I play him some just to stay sharp, and he's also one of my favorite picks for top/mid and even in the ADC role (since Renekton is manaless he plays the cleanup role very well). He's the most fun in support role though; here Renekton can forget about Q ranks a bit and focus on catching/killing enemy champions, which is more fun. I also like being in the bot-lane with him generally, where there is more action. Renekton is suited to the chaos since he dashes around so much and is hard to bring down.