I been reading The Old Republic comics, and the best ones are the Blood of the Empire miniseries. Features Darth Thanaton, a character who is a main villain in the game. It really fleshes him out more, and shows he was a capable Sith.
Other Respect threads I have made.
"Philosophy gives structure to the delicately ordered chaos of our Empire. Tradition. Principles. History. The threads that compose our society."―Darth Thanaton
Long story short, he started out as a Sith Apprentice whose master fell from grace. Thanaton was sent on a suicide mission to kill the Emperor Vitiates former apprentice Exel Kreesh, who was both a highly skilled and powerful Sith. He ends up succeeding this mission, and then becomes part of the Dark Council of the Empire. Later on in the war, he bites off more than he meant too, and was destroyed by a powerful Sith called Kallig. Kallig was able to defeat him due to being possessed by force spirits that end up throwing off Thanatos. If not for this special use of the Force, Thanatos would have won.
Like all Jedi Thanaton is a powerful Telekinetic even among Force Users. He also actively used this ability in combat all the time. He shows excellent mastery of TK, and applies its use in any fight whether to attack his foe, or use the environment to his benefit.
TKs his Lightsaber to kill Exel Kreesh with a sneak attack.
Uses it for a typical Lightsaber throw to cut down multiple guards. Also shows to TK the guards blasters away from them before attacking.
Weilds shattered glass as a weapon.
Impressive feat of easily blowing past the Force Defense of his former Master in mid combat, and slams him around.
Uses TK to force two droids to shoot themselves while being shot at in the air.
Uses TK on a large stone column piece. turning it into rubble.
With one hand, Thanaton lifts and moves car size wreckage pieces of starship.
Shows the power to make a bridge that is over 100+ feet out of ship wreckage in the vacuum of space with no space suit.
By far Thanaton's go to Dark Side power was his powerful use of Force Lightning. He regularly shows the use of force Lightning in fights, and it is proven to be a fall back move for him.
Uses it against his former Master in combat.
Blows up a stasis tank, and openly tries to wield Force Lightning against Kressh.
Uses it to kill a Gargantuan.
Thanaton's Force Lightning is so powerful that he can summon Lightning all around.
Thanaton also showed he can summon it on his target from above.
Fully shows the ability to gain temporally flight from the power of his Force Lightning.
Able to form Force Lightning into a barrier. Even a Force spirit amped Darth Nox was electrocuted and stopped by it.
His power in TK and Forc Lightning is so good, he even showed the use of Force Maelstorm in the end fight with Darth Nox. Lightning rains down on the Force Spirit enhance Sith, and we see the debris flying around the devastation.
Later in his life, Thanaton is able to use Force Lightning to such a degree that he can cover a area around him in Lightning, and even show temporarily flight by being propelled by the Force Lightning's power alone.
Force Leap and Speed
Like all Force Users, Thanaton shows the skill to enhance his stats for increase of jumping, falling, and speed.
Falling from great heights out of a Starship.
Falling from great heights, and even onto a fast speed tram.
Uses Force Leap to jump high above attacking Droids. Also shows the speed to maneuver between Droids blasters.
Spins his double Blade Lightsaber fast enough to form a webbing.
Reacts to Force Lightning.
Thanaton had shown the ability to use Farsight when he was young. Able to foresee his own future.
Thanaton meditates and foresees his future, as well the place to hunt Exel Kreesh.
Jedi Mind Trick
A common ability that Thanaton had shown to known and used.
Thanaton uses it on a guard.
Thanaton demostrated incredible pain tolerance, and clear use of the Curato Salva ability.
The Force Lightning of Exel Kreesh was very powerful. killing super human durable Aliens with a single blow. Thanaton withstands not only a direct hit from it, but also sustain its powers as it traveled along his Lightsaber hilt, and onto his hands.
After nearly being killed in his first meet up with Exel Kreesh, Thanaton through many mortal wounds travels across a desert, kills a large Gargantuan, meditates for a night in a state close to death, and then still has the energy to have a quick spar with a Jedi Knight.
Here a older Thanaton even tanks the overwhelming amped burst of Force Lightning by Darth Nox. It flings him across a large area and into a wall. He gets up and retreat.
Thanaton was a very prominent Sith Sorceror before his death.
Before his death, he showed to understand and use a powerful Sith Spell that killed his foe Kallig when she came to kill him. After killing his Apprentices, he speaks a few words, and kills her, as well her partner, with this single spell. It was only due to Kallig being save by Force Spirits that she survived this attack, though she was dead.
Thanaton wields typically either a Double Bladed, or Single Blade Lightsaber with a Red Synthetic crystal.
While their is no info on his Forms that he use, it is safe to say he does use Juya since it was a typical Sith style of the time, and the Double Bladed Lightsaber further hints at it. We can also assume he knows Niman as he uses his Force Powers in a fight with his Lightsaber all the time.