Which beings in the DC or Marvel universes could defeat Zatanna of the JLA? Thor? Sentry? Hulk? Blue Marvel? The Phoenix (Jean Grey)?
I saw this list of Zatanna's powers in a discussion on Marvel.com:
Sorcery: Zatanna is a magi, a human born with the affinity to manipulate magic. Her unique genetic structure allows her to use the magic she was born with as well as learned magic. As a tribute to her father, and as a focus for her spells, she casts spells by speaking backwards. For example, saying "pots" would cause the target of the spell to stop in their tracks. She can only cast the spells she wants by speaking or reading backwards, because that's the only way to focus her magic.
Elemental Sorcery: With her magic Zatanna has shown a greatest affinity to manipulate the elements of the Earth.
Pyrokinesis: Generation and Control of fire
Aerokinesis: Generation and Control of Air
Geokinesis: Control of Earth/Rock
Hydrokinesis: Control of Water
Cryokinesis: Generation and Control of Ice
Telepathy: Zatanna can use her magic to manipulate the minds of others. She has displayed the following abilities.
Memory Manipulation: She is able to wipe minds completely and/or remove specific memories.
Chlorokinesis: Control over plants
Thermokinesis: She has used this ability a few times to stay warm in frigid environments.
Teleportation: Able to teleport herself and/or others to anywhere she desires.
Magical Awareness: supernatural sensitivity to occult activities and mystic phenomena.
Dispel: Able to remove illusions and holographic images that her opponents have set up.
Regeneration: Able to heal herself and others
Size Alteration: She can increase or decrease her overall volume to nearly any size she chooses. The limits of this ability are subject only to the degree of power available to her at any one time. She has been seen using this ability to get down to the size of the Atom (about 6 inches tall at the time) to talk to him face-to-face.
Spectral Sight: She can see spiritual entities and travelers invisible to normal sight; she can perceive magical events at a great distance.
Elemental Transmutation: Zatanna has the ability to rearrange atoms and molecules in both inorganic and organic matter. She can change an objectâ€™s or creature's shape. In addition from one chemical into another.
Magical Manipulation: Zatanna is also capable of using all personal and universal magic
Extraction and Transportation of Souls: Able to extract and move souls from organic/inorganic structures to another organic/inorganic structure. In addition, she can attack her opponents by thrusting a soul at them. She only does this ability in dire situations.
Mystical Invulnerability: After casting this specific spell, she is safe from any offensive magic that comes her way or others.
Abilities Prestidigitation: Zatanna is skilled in stage magic, performing simple tricks and elaborate illusions.
Good Combatant: She has also been taught conventional fighting skills by the Justice League, but favors using magic in place of them.
Occultist: as Chronicler of Magic she possesses an extensive understanding of Occult lore due to her Mystic Background
Improvisation: She prepares specific spells (a couple of hundred) but improvises a good bit for the unpredictable situations she encounters.
Bi-Lingual: Able to speak English and "Backwards Speech". As noted throughout the comics, she doesn't show any difficulty in speaking backwards when performing spells. It seems she can speak backward speech without hesitation and with clarity. Backwards Speech is most commonly known as Mnemonic Incantations.
Strength level: As a magician, she is considered among the most powerful and knowledgeable in the world and often works alongside the most powerful magic-users on Earth, including Doctor Fate, Madame Xanadu, and Captain Marvel. However, the actual extent of her powers is not fully known. According to Green Arrow, she is the most powerful member of the Justice League. Of all the magicians and sorcerers on the planet, the JLA always go to Zatanna when they need magical assistance.