Damien Darhk's powers and abilities
Dark Magic
Damien's powers came from the Khushu Idol, a mystical totem he acquired in 2011 that channels and harnesses primordial energies; specifically energies that come from death, destruction, and fear. The more Damien kills the more powerful he is at that moment, but gradually the power that he gains from that death will fade soon afterwards thus he must continue to kill in order to continue to use his magic. Damien's skill with dark magic is proven to be considerably advanced, as he is well known for his power among the world of occult and he is so skilled in dark magic that even John Constantine, a master sorcerer in his own right, did not dare face him; implying that Damien is far more powerful than John. After causing the deaths of tens of thousands of people through the nuclear bombing of Havenrock, Damien's powers grew exponentially to a level even he wasn't aware of causing him to exercise more focus and control on using his powers. After being resurrected, Damien Displayed the ability to use his magic powers even without the aid of the idol.
Accelerated Healing
Damien gains advanced regenerative abilities. He was shown to be able to heal after being shot at by bullets and arrows. His healing abilities also seem to prevent him from suffering from fatigue and has been able to quickly recover from the effects of sedatives.
Enhanced Endurance
Damien gains inhuman levels of resilience, to the point where he could be shot repeatedly and be completely unfazed by it.
Enhanced strength
Damien's physical strength becomes far greater than a normal human. Damien was strong enough to effortlessly lift a fully grown human over his head with a single hand, send a Time Bureau agent flying with a single kick, snap Oliver Queen's steel arrows with one hand, and throw Oliver with enough force to deform a metal pole.
Life-Force Absorption
Damien can siphon the life-force from people and kill them through physical contact. According to Damien the process is quite painful, in addition it allowed Damien to take the darkness of the person he absorbs to add to his powers at the moment. After causing the destruction of Havenrock, Damien's power was strong enough to try and absorb the life-force of Oliver, despite his use of Light Magic.
Telekinesis
Damien can move and otherwise exert force objects and people with his mind. This notably allowed him to could stop and launch multiple projectiles or to crush objects, such as a TV or an armored truck, without physically touching them. He could also use his abilities to physically attack people from a distance, even if they are in different country, seen only through a video screen. He notably was able used this ability to immobilize, choke, strangle, levitate, and send people flying across rooms through mental effort and gestures alone. After causing the destruction of Havenrock, Damien could use this power to disintegrate objects with his mind such as steel arrows and lead bullets. Damien also demonstrated the ability to contain and miniaturized an explosion with this power.
Teleportation
Damien can instantly transport himself to another location, allowing him to catch his enemies off-guard or leave an area without a trace. The range of this power is unknown, but he could teleport himself with at least one other person.
Electrokinesis
Damien can control and generate electricity.
Longevity
After leaving the League of Assassins, Damien stole water from the Lazarus Pit, allowing him to live far longer than normal human without aging while maintaining his health, vitality, and appearance. With the waters, Damien has lived for at least as long as his former friend, Ra's al Ghul, making him well over a century old. Given how Damien did not have access to all of the waters of the Lazarus Pit and that they gradually lose their potency over time, it is possible that Damien's life-force absorbing abilities granted to him by his idol also allow him to maintain his youth.
Temporal Awareness
After being resurrected, Damien showed that the mind-wipe that Sara Lance has performed on him wore off, allowing him to remember his time travel adventures as a member of the Legion of Doom.
Abilities
Peak Human Physical Condition
Even without his physical strength, durability and healing augmented by his idol, Damien is still in outstanding physical form due to centuries of training and experience as well as being kept in peak physical condition by the Lazarus Pit's waters, although due to his reliance of magic, it has reduced considerably, as shown by how Oliver was easily able to defeat Damien, until he seemingly had retrained himself, regaining enough of his physical finesse to take on Oliver equally and even at times gain the upper hand in their final fight even without his magic. At his prime, Damien could easily overpower Sara even when she had her staff, able to block her strikes with his forearms without suffering any damage.
Master Combatant/Martial Artist
Due to his training as a former "Heir to the Demon" and having centuries of combat experience and training, Damien was a combatant of outstanding, almost unrivaled skill, having been the equal of Ra's al Ghul himself. As a former member of the league, Damien was trained in all of their ways with his skills far surpassing most members due to his former status as an "Heir to the Demon" and thus having received the highest level of training a League of Assassin member could have. His skill has allowed him to go toe-to-toe with and even defeat the likes of Malcolm Merlyn, Oliver Queen, and Sara Lance. However, once Damien became a sorcerer, he developed an over-reliance on his supernatural powers granted by the Khushu Idol, causing his prowess as a combatant to noticeably decline; this was perhaps best highlighted in his younger 1987 version, who proved to have much more combat-finesse than he will be in the early 21st century, as his younger-self has yet to acquire the idol and it's mystical benefits at the time, at which point he was able to swiftly defeat Sara in hand-to-hand combat and even dominate Sara using her signature weapon as well as eventually defeating Malcolm in their duel. It appears that while magic gave him full access to his original level of skill, losing it can briefly deprive him of his combat skill, as while he proved to be able to easily defeat Oliver after he received League of Assassins training while he was rusty from months of not fighting and remain on equal footing with Oliver after he got back in shape as well as overpower Malcolm, once deprived he was swiftly beaten. In spite of that, Damien appears to have retrained himself after getting out of prison as while his magic was unable to be used against Oliver due to Oliver's light magic, he was still shown to be able to fight him on equal footing and even at times dominate and knock him down twice and disarm him of his bow, only barely losing. His skill marked him among the most dangerous fighters of the multiverse.
Master Swordsman
As a former member of the League of Assassins, especially as a former "Heir to the Demon", Damien has received extensive training in swordsmanship. Although not often used since he left the league, his training and years of experience had nevertheless allowed him to keep his skills with a sword. He displayed immense skill in swordsmanship, able to easily match Malcolm Merlyn in their duel and even briefly push him back. He also has twice been able to fight equally against Sara Lance after she was retrained by the League in a sword fight before being beaten.
Master Marksman
While not his preferred method, Damien's extensive training as a former "Heir to the Demon" and his long lifespan has made him quite proficient in marksmanship, although not quite as skilled with firearms as he is with a sword or archery as he himself admits, displaying great accuracy and precision with a laser gun, able to single-handedly easily take out many guards in a firefight and even shot one at broad sunlight
Master Archer
Although not his favorite style, due to his training as a former "Heir to the Demon", Damien has received training in archery and has displayed a high amount of skill, being able to fire an arrow from Oliver's bow accurately, hitting the latter in the shoulder at point blank range and would have incapacitated him had it not been for Oliver's armor.
Master Knife Wielder
As shown from his method of stress-managing, Damien is very accurate with knife-throwing. He is also capable of skillfully using knives in single combat, evidenced when he fought Malcolm.
Genius-Level Intellect/Master Tactician/Leader
Damien, due to his extended lifespan, was able to gain the wisdom from many ages and has proven himself to be highly intelligent, having a quite extensive knowledge of various subjects such as criminal enterprises, politics and science. As a sorcerer, Damien possessed vast knowledge of mysticism including details on his idol, the Lazarus Pit and the Anansi Totem. Using a blood ritual, Damien was able to maintain his sanity while using the Idol's powers. Damien was also collector of rare occult and historical artifacts even before attaining his powers. He was a very capable leader, as he was the founder of H.I.V.E. and was able to lead it in secret so effectively that he was able to completely hide the organization's existence from the world at large and was clever enough that he was capable of both leading and keeping his organization's secretive nature while simultaneously avoiding capture from his former friend, Ra's al Ghul, for over a century. Damien is also very perceptive, able to tell that Speedy was trained by Malcolm and Sara's fighting style was of the League of Assassins. He was able to deduce all the other identities of Team Arrow once learning Spartan's identity.
Master Interrogator/Torturer
Damien was a highly skilled torturer due to his training with the League as well as his psychopathy and genuine pleasure in inflicting pain. His skills proved valuable in extracting vital information from an amnesiac Rip Hunter which lead to the restoration of his memories and conversion to the Legion of Doom. As a sorcerer, Damien had built up as fearsome reputation so much that a noted sorcerer like John Constantine feared facing him.
Multilingual
Damien was capable of fluently speaking English, German, Russian and presumably Arabic due to his former status as an "Heir to the Demon".
High Pain Tolerance
Even without his magical powers, Damien has demonstrated a high threshold for pain due to his training with the League of Assassins; he was able to pull out arrows from his chest and still continue to remain physically active with little effort.