In this thread I am delivering my findings on fighting Stygian Dragon 1V1. While the template is not my creation, I will throw in a nice trick specific for that encounter I discovered myself.
First of all: what is the template?
1) skills

I am using resists because it s very handy when you solo spawns like Primeval Lich or Abyssal Inferno. For Stygian Dragon, you can go for something else, like bushido for lightning strike for example.
2) stats

Here are my stats without pots. Going to 150 str can be handy for the additional hps (its double special can be devastating at time).
3) The wep

You want to have as close as 100 as you can. Even though you'll mainly use AI you could be hitting for much harder with a 100% cold soul glaive than what I am using. Unfortunately, the 100% soul glaives with the right mods are extremely hard to make.
The Dragon slayer doesn't pump as much intensity as reptile, and assures you that you re going to always hit at the 300% damage limit. The 40% DI, along with the 60% on my suit, will allow me to cap the base damage as well. I have 30 SSI so with the 15 SSI I have on my suit (berserker+cloak), I will swing at 1.5sec/hit. The HML will help me to get mana back when the Stygian Dragon is out of mana.
II Getting the keys
To get the keys you need to kill the spawn of the Ancient Wyvern [renowned], located in the abyss at the following place:

The spawn starts with fairy dragons and then wyverns. Your dragon slayer will cap your damage on both of them. The last level is ancient servants, and only Enemy of One will help you deliver more damage on them. The boss is subject to dragon slayer as well. Overall, that spawn provides good items, so it's worth doing it until the boss (included) even if you have your set quickly. In my case, someone had dropped the keys on the ground so it went fast...

The keys are those blueish bubbles called Draconic Orbs. You need 4 of them. Once you have collected enough, you head to the western part of the spawn, climb the stairs and keep heading west in a long corridor until you reach the altars.

Once there double click a altar then an orb, rince and repeat for all 4 of them. The ones that seem already placed are not actually placed, it's probably a hint but more confusing than anything. So you really need 4. A gate will then open and you can enter the arena! Note that this arena allows recall out, it may be a good idea to cancel your emergency recall macro, if you have any.
III) Fighting Stygian Dragon
1) the trick
When you enter the room, go to the south teleporter and use it:

Then follow the corridor until you reach another teleporter:

That teleporter is magic, it will teleport you one floor higher, to the other side of the corridor.

The Stygian Dragon has no troubles flying from one of those teles to the other. You should train a bit using them, since you can't take them from every direction.
Once you are good at using them, and sure you wont panic mid fight, go pull the Stygian Dragon.
Pingpong between the two teleporters and use aids to heal yourself whenever it s needed. Spam AI as much as you can. If you die, you can res on the eastern side of the corridor, but it's no use dieing. You should'nt die if you play carefully, by teleporting instantly upon having your health bar decreasing. You don't need to move, Stygian Dragon will be on you within seconds. Sometimes, when he decides to rest, you can go to the previous teleporter but always with max health first.
After 5-10 minutes you'll have killed the Stygian Dragon:

Hope you have liked that tutorial