Nova derives his powers from an energy source called the Nova Force, which all Nova Corps Centurions wield. This energy was transferred by Xandarian technology to Rider by the Nova-Centurion Rhomann Dey. Nova's small measure of the Nova Force gives him superhuman powers including flight, superhuman strength, speed, and durability, as well as the power to absorb energy directed against him and release it as gravimetric pulses and beams, either from specific parts of his body or from his entire body.
Nova wears a standard Xandarian StarCorps uniform, designed to accommodate his powers without being damaged by them. The uniform is highly resistant to damage, including outer space conditions, and is airtight. The helmet contains a plexiglass-like plate that can be lowered to cover the lower face by cybernetic command, thereby making the helmet airtight; the helmet is connected to an oxygen supply concealed within the uniform. In addition, the uniform has a built-in life support function that can sustain Rider under the most extreme environmental conditions, including acting as a life-support suit by locking off the mouth and eyes of the helmet. The helmet contains radio circuitry enabling Nova to pick up radio transmissions, monitor transmissions, telescopic sights, night vision sensors, and heat imaging sensors, as well as overlay a visual heads-up display for tracking energy signatures. Nova's helmet has a rigid construction and shape when worn, but becomes as malleable as cloth when it is not, allowing Rider to hide it in his civilian clothes when desired.
Rider can also alter the appearance and nature of his uniform to suit his needs. However, as Rider learns the hard way, the StarCorps keeps a strict dress code. When he makes major cosmetic changes to his uniform after rejoining the New Warriors, Nova is summarily ordered to conform to standard.
Nova's uniform is not only extremely malleable; it is also designed with specific weapons and functions to aid Rider in his role as a Nova Corps Centurion. Among these features are an electromagnetic discharge that can nullify gravity and access to StarGates that allow him to enter hyperspace, where he can move at velocities exceeding the speed of light.
Nova is a good hand-to-hand combatant, and has been coached by Chord.
During Annihilation, Rider's uniform is altered and enhanced to house the Xandarian Worldmind and aid him in containing the Nova Force. As host to the entire Nova Force, which was previously used to empower all members of the Nova Corps throughout the universe, Rider is now possessed of tremendously augmented strength and durability as well as nearly limitless quantities of energy. However, he's now bonded to the Nova Force itself, and unable to survive for long if separated from it.
In addition to the Nova Force, Rider's body currently houses the Worldmind, the entire culture and history of Xandar as well as the individual minds of thousands of years of dead Xandarians. The consensus voice of the Worldmind can speak directly to Rider, and has demonstrated the following capabilities:
* It helps Rider contain the whole Nova Force while keeping his mind and sanity intact.
* It downloads profiles of opponents directly into Rider's mind.
* It detects nearby energy surges, including those used in teleportation.
* It can assume control of Rider's body as he sleeps.
* It can access other computer systems, including heavily-protected terrestrial computer networks such as S.H.I.E.L.D. records.
* It analyzes attackers, including detecting adrenaline surges in their bodies.
* It detects approaching super-humans with energy-based powers (like Penance).
* It enables Rider to hack into satellite TV broadcasts, and transmit his voice and image to individual TV sets.
* It can protect Rider from psionic manipulation using psi-shields.
http://en.wikipedia.org/wiki/Nova_%28comics%29#Powers_and_abilitiesThe Scarecrow uses a variety of toxins that cause his victims to hallucinate that their phobias have come to life. He wears his Scarecrow mask to enhance the effect of the hallucinogen (instilling fear in all who see him) as well as to avoid being poisoned by his own toxin. Although not physically intimidating, Scarecrow can resort to physical combat, using a style called "violent dancing", based partly on the crane style of kung fu and on drunken boxing.
The Scarecrow is an expert on psychology, with a focus on fear, and is a certified professor on the subject. Due to prolonged exposure to his own gas, Scarecrow went from being frightened of bats to only being frightened of Batman.
Scarecrow is both addicted to fear and incapable of fearing anything except Batman, whom he compulsively seeks in order to ease his addiction after the Caped Crusader's apparent death. Scarecrow is chosen as a bearer of the twin of Sinestro's yellow ring as a temporary Corpsman, giving him the powers of a member of the Sinestro Corps.
The Scarecrow at times wields a scythe which he uses in addition to his 'violent dancing'. Scarecrow also uses a hand-held fear gas sprayer in the shape of a human skull, straws which he leaves as a calling card, special straws which can be snapped in half to release a fear toxin (as seen in Batman: Hush), stuffed scarecrows which scare his victims, and, most recently, a Yellow Lantern ring (as seen in the Blackest Night mini-series).
http://en.wikipedia.org/wiki/Scarecrow_%28comics%29#Powers_and_abilitiesIn short this is Scarecrow as we're used to seeing him, only weilding the Yellow Lantern (Sinestro Corps) ring. Yellow represents Fear on the Emotion Spectrum. So you have a guy who lives for fear weilding a weapon that can generate power based on the wearer's ability to create and control Fear.