Meralygos

 Green dragons - How do they fight?

Green dragons as they are secluded creatures. Nonetheless, we have quite a few encounters with them, both as allies and enemies, during World of Warcraft. A surprisingly swift flight, they often move quickly, teleporting through the dream to wherever their thoughts lead. Time is meaningless inside the Dream and as a result the green dragonflight is extremely long-lived. 

 Somnus was the first encounter. He was a drake with a corrosive  Acid Breath attack and a  Sleep spell.

 Wardens of the Dream - Dreamscythe, Morphaz, and Weaver, drake guardians of Eranikus who all have two abilities, Wing Flap and Acid Breath.

 Rothos -  Acid Breath and  Fade ability. Later in Legion, his corrupted version has a "gloom" ability, which makes a nightmare fall from above.

 Dreamstalker - Acid Breath and Sleep ability.

 Phantim - Acid Breath and Summon Illusions (that attack the party).

 Dreamtracker - Breath and Bellowing Roar

 Shade of Eranikus.  Deep Slumber (dragon luls a player into sleep for 10 sec, stunning them and making them invulnerable), trash (attacks twice in a row), war stomp, Acid Breath, knockback ability. High nature resistance. He has his eyes closed and can see regardless.

 Eranikus also appears in the World of Warcraft comic fighting Lo'gosh and Broll Bearmantle. He has the ability to become intangible at will, entering the Emerald Dream to avoid physical attacks. 

In the Stormrage novel, when he manifested onto the physical world, Eranikus shimmered lightly, not entirely attuned to the material world and still connected to the Dream.

   The Four Dragons of Nightmare. Ysondre, Lethon, Tearar, Emeriss. All had a  Mark of Nature ability. They also used an acid breath or a corrupted breath (in the Legion version):  Corrupted Breath or  Noxious Breath - acid breath that deals nature damage and applies a DoT which stacks up to 6 times. All had  Tail Lash and  Seeping Fogs. In Legion, they trap players into  Slumbering Nightmares. Despite being killed multiple times in their physical form, their spirit remains in the Emerald Realm, alive.

Furthermore, they had unique abilities.

 Lethon. For example, Lethon used a shadow bolt volley and then drawed the spirits of their victims.  Siphon Spirit is the ability. "Lethon pulls a soul fragment out of players, drawing them in towards himself. When the spirit reaches Lethon, it heals both him and Ysondre for 17062500 health. Lethon uses this ability while grounded."  Gloom is ability added in the Legion encounter, causes nightmares that fell from above.

 Tearar.  Taerar splits his essence into two images of himself. Two Shades of Tearar, who have much less health than he does and attack his enemies. They also have acid breath abilities. He also uses Bellowing Roar.

 Emeriss.  Corruption of the Nightmare, everytime an ally or an enemy dies, a nightmare mushroom sprouts from the earth.  Corrupted mushroom do burst, exploding and dealing damages to everyone. He also has  Volatile Infection. 

 Ysondre, instead, used  Lightning Wave and  Summoned several druid spirits corrupted by the nightmare. In her corrupted version, she uses 

 Alysra. Used Acid Breath and a volley of green firebolts (nature bolts? or something).

 Valithria Dreamwalker. Can be found as a caged prisoner in Icecrown Citadel. She used  Nightmare Portal,  Emerald Vigor,  Dreamwalker's Rage.

 Emerald Drake (in the Oculus encounter).  Leeching Poison.  Touch of Nightmare.  Dream Funnel. 

 Shar'thos. Nightmare breath, Tail Lash,  Burning Earth — Shar'thos ignites the land, inflicting fire damages.  Dread Flame — Shar'thos spits a glob of Dread Flame at an enemy that will bounce to 5 nearby enemies.   Cry of the Tormented — Fears all enemies within 60 yards for 5 sec. 

 Dresaron. Breath of corruption. Wing flap, Earthshaking Roar.

Green Dragons. Such as Thessera and Desharin make a few appearances during quests. Thessera releases green bolts of magic, like nature bombs or something.

Similar green power is mentioned in the novel Stormrage, where an army of green dragons makes the nightmare essence retrocede. Green dragons could also make lesser races levitate and lift in the air. In general, they could release life energy (and dark, twisted life energy if turned into nightmares).

 Ysera. 

Dawn of the Aspects: When in combat, she attacks with a greenish breath (which Malygos recalled as a breath weapon akin to that of Galakrond's, if not so debilitating), to put her opponents to sleep, and rarely strikes to kill. She prefers to neutralize her enemies and banish them away from her realm. Later on, she is able to cure a frightnened dragon from a bloodlust disease.

Ysera's greenish breath was used also in the Twilight of the Aspects. She exhaled breath that looked "as sweet as summer flowers" but that, in truth, was sickly and toxic. She also sent nightmare and illusions towards their enemies, making them perceive a misguided reality: for example, she tricked two twilight dragons into believing their comrade was the enemy and thus they began to fight each other. 

Always in the Twilight of the Aspects, she claims to have "seen everything in the Dream, even what did not exist". Apparently, her visions lacked some coherence, as her dreaming (for over 10,000 years) left her a bit disoriented once she awakened. Ysera's visions were much like a dream - a bit incomplete, a bit incoherent - yet still capable of showing future events: for example, she saw in her vision the Hour of Twilight. In this vision, much was still incomplete as she couldn't decipher the face of the future Aspect of Magic. Such visions didn't show a definitive future: much like dreams, they didn't show the entire of the reality and could be altered or even modified. Yet, the vision revealed extremely helpful as it made the Aspects aware of the Hour of Twilight and the powers that Chromatus possessed, allowing him to counter-attack the beast in an efficient way. Her way of battling was defined mercurial - somewhat erratic, trying to be unpredictable to the opponent so that they wouldn't know how she'd attack. She also displayed healing powers. Once the entire Aspects were fighting as one, they gained a new ability, a white empowered breath that was described as "breath in the shape of a flame, the purest white hue Thrall had ever seen". In the book, she looked detached from the material world and instead deeply tied to other being's emotions and hopes. 

In the War of the Ancients trilogy she can communicate to mortals in their minds. She also blessed the World Tree so that it may be bond to the Emerald Dream and represent the hopes of prosperity for the kaldorei.

In the novel Stormrage, Ysera and all green dragons could communicate with druids through a mental link. When she opened her eyes to Lucan, the following happened: "The eyes of Ysera carried within them a kaleidoscope of images all tied to Lucan…and every other creature that dreamed. He became a part of each one of those dreams and by doing so opened up the most hidden parts of his subconscious to the dragon."

In the Day of the Dragon, she opened her eyes to Rhonin. "Ysera faced him—and her eyes opened. For a brief moment, vertigo seized control of the human. The dreamlike eyes that stared back reminded him of everyone he had ever known, hated, or loved."

Always in DoftD, she also displays the ability to induce others to daydream: they become unaware of their surroundings, filled by their own hopes and thus distracted: "Then Deathwing noticed a complacency in himself, a satisfaction that grew to distraction. Almost too late he realized that he had begun to daydream. Shaking his head, he quickly dislodged the cobwebs that she had cast within his mind—just as all three of his adversaries tried to seize him in their talons." She also has the ability to send nightmares into other being's head - their worse nightmares!

She has the ability to planeshift between the real world and the Emerald Dream. Likely, she can do so nearly istantly, while for other dragons and druids it may take more time.

In Cataclysm. She uses two abilities in the encounter 'Madness of Deathwing'. Ysera Presence (healing increased by 20%) and Enter the Dream (The Presence of Ysera allows players to enter the Dream, decreasing damage taken by 50% for 2.50 sec.).

In the Legion questline, Ysera displays a spell, Wrath of Ysera, a nature bomb casted from her mouth which deals an huge amount of damages. When corrupted, she uses "Cries of Insanity", Nightmare Breath, Taste of Blood.

Her spirits remains in the Emerald Dream despite her physical death.

Her spirits casts a Dream Simulacrum in the battle against Xavius. When Xavius reaches 95% and 60% health, the Dream of Ysera puts half of the party into a Dreaming State. Affected players fall asleep while a Dream Simulacrum of them rises to fight Xavius. If the Dream Simulacrum should ever die, the player's actual body will awaken. All Nightmare Corruption gained by the Dream Simulacrum is lost when the player returns to their body.

RPG - Green dragons avoid combat, preferring to use incapacitating magic or their breath weapons to stop their foes. If pushed, however, they fight to the best of their abilities, using quick thinking and their magical prowess to outwit and outmaneuver their foes. Unlike most dragons, greens call upon the power of nature for their magic, and this gives them one major advantage: healing magic. If necessary, a green drake wears down her opponent, then flies away briefly to heal before reengaging. In battles with allies, such as other dragons, a few green drakes often stay back to heal their group and use beneficial spell-like abilities.

Green dragons have no enemies in the Emerald Dream, but they know that the world of Azeroth is not as lucky or as peaceful. They are capable of fighting, but choose not to if there is any option other than their own death. If conflict is unavoidable, they try to neutralize foes with their breath weapon and leave the area. Some consider green dragons to be pacifists or weaklings. Those who have roused a green to combat fast learn the error of this opinion. After all, dreams and nightmares are not so very different.

Interpretations.

 Acid Breath  Cloud Breath. Green dragons have displayed two main types of breath so far, an acid breath - corrosive and capable of melting beings, inflicts nature damages. They also release an air breath, exhaling noxious fumes or green clouds.

In the Twilights of the Aspects the Cloud Breath looks "sweet as summer flowers" but is sickly and toxic. 

 Seeping Fogs. Green dragons can exhale fogs or green clouds that look sickly - perhaps acidic in nature? - that throws everyone that stands inside into a dormant state.

 Venom. Green dragons often use venomous attacks, twisted as bolts, clouds or breath attacks.

Nature Magic and Life Magic:

It is not clear if green dragons' mastery of nature magic works in a similar way to the other races: do they have to make a request to the lightning to unleash a storm? Being so attuned to the elements of nature it's not clear. As they can unleash storms of lightning even if they are corrupted, their connection to nature is linked to their will aswell. Being so attuned and magically gifted, perhaps green dragons should already be deemed a part of nature itself hence their magic of nature is [speculation] something inbetween an extension of themselves and a demand to nature. 

 Lightning Magic. In general, green dragons managed to control the forces of nature much akin a druid does, summoning the forces of nature and summoning waves of lightning. 

 Life Magic. Their connection to the dream grants them power over life magic and nature magic, akin to a druid. They can channel and unleash life energy to both heal and destroy. Life energy requires actual life to be used. Life magic is a form of nature magic.

For example, the spell  Dream Funnel of the emerald drakes in the Oculus actually transfers the drake's own health to an ally. The Dragons of Nightmare were capable of making great, corrupted mushrooms grow from fallen victims. Once more, this stands as a testment to the powers over nature they do possess.

 Dreamwalker's Rage. Life Energy can be unleashed in many forms and is very versatile. Likely, it was used as a powerful explosive nova by Valthiria Dreamwalker, which funneled life energy to destroy the group of undead minions that tried to twist her. It can also be unleashed as bolts of life energy - such was likely the ability displayed by Ysera, Wrath of Ysera.

 Leeching Poison. Through certain abilities, green dragons can drain the health of their victims. For example, the Emerald Drake could apply a poison to his enemies (named Leeching Poison) that would siphon the target's health. This is an indication of both their venom and life magic prowess.

 Siphon Spirit. Their ability to drain health is further expanded by Lethon's siphon spirit ability. Lethon indeed severes a part of the soul from his foe's body. The severed soul tries to reach Lethon. Unless stopped, it will heal him.

Disease - If corrupted, a dragon's power over life turns into the power to harvest and unleash diseases.

 Burning Earth - In its corrupted form, Shar'thos altered the earth, making it burn in flames. Likely, green dragons possessed the opposite ability: to make life grow on the surface through life energy.

Dreamers of the Dream

 Sleep. They can induce their enemies to fall into dreams (or nightmares). On certain occasions, perhaps they can even send them to touch the Emerald Dream in the forms of deep slumbers, such as the one used by Eranikus. In this variant, the afflicted entity almost fades from this world and becomes ethereal. This spell is indicative of their peaceful and nonviolent nature; for example, in one variant used by Malfurion the spell caressed their targets like a soft breeze, inducing them to sleep.

 Touch of Nightmare. Dragons can send nightmares into their foes (or friends, that is) or even induce them to daydream and see a misguided reality. 

 Gloom - to some limited extent, a few fully-corrupted Nightmare Dragons such as Rothos could make material manifestations of nightmares descend from the sky. They were shadowy dark substances.

 Summon Minions. Green dragons - or atleast their corrupted kinsmen - could summon creatures from the Dream. Eranikus and Ysondre both did so.

 Nightmare Portal. Green dragons can shift from the Emerald Dream to our world and inbetween. They are capable of switching to this world to their Dream, albeit doing so requires a certain meditative state. More often than not, once they stop being in the Emerald Dream (stop dreaming) they become slightly disoriented.

 Connection to the Dream. Their connection to the Dream allows them to be serene and quiet. At the same time, it strenghten their connection to nature and shapes their powers in a druidic way.

 Manipulate emotions: To some extent, albeit limited, green dragons can manipulate emotions. The presence of Ysera was said to induce a peaceful state, that people felt a warm presence when they approached her.

Furthermore, corrupted dragons also have the ability to induce negative emotions (such as fear or anguish) through their spells. For example, Ysera used the ability Cry of Insanity and an other nightmare dragon had the ability Cry of the Tormented. Most likely they induce such visions as they induce nightmares of their own victims.

 Summon Illusions. Green dragons can summon illusions. In the Twilight of the Aspects, it is mentioned that Ysera summoned illusions inside the head of the beholder - perhaps they are not like the mirror images summoned by mages. They can indeed weave illusions inside the opponent's heads.

 Fade. Green dragons can fade from this world partially, becomming intangible to physical damage and many forms of attacks (fire magic for example). Granted, they are still vulnerable to other forms of magic, such as corruptive ones.

 Visions. Green dragons can see much from the dream - even have visions from the future, albeit this is a limited occurrence and partially subconscious. It is further expanded in the Ysera section. 

Conclusions. 

 Green dragons are quiet and non-violent dragons. They have no interest in being belligerents spirits and rather the peace of their Emerald Dream. In fact, most green dragons we fought were indeed enemies that succumbed to the Nightmare.

 They will likely refrain from fighting, if possible, as they loathe violence. If engaged, they may unleash their poisonous abilities as they strike the enemy. They will likely engulf their challangers into noxious clouds exhaled from their mouths, disorienting them before they strike (or, alternatively, retreat as they are uninterested in battles).

 When in battle, they use their mercurial and swift nature to evade from many hits and play on swiftness over brute strength. As they do so, they send nightmares and dreams into their opponents, making them become distracted or misguiding them into fighting one another. 

 They have similar abilities to the druids and can indeed unleash lightning and nature magic in general. 

 Alternatively they focus on summoning shadows and illusions from themselves, such as shades of themselves, to induce fear into the opponent and deceive him into attacking in the wrong direction.

 They appear to be built more for emotion's manipulation and deception, swiftness and rapidity, than strenght and magical power. They know very few arcane spells and use magic of nature instead.

 Other than manipulating emotions and summon beings from the emerald realm - aswell as twisting their shadows - emerald dragons can unleash their energy as life energy, healing themselves and making plants and stuff grow. Releasing life energy costs... well, life energy, so they should pay attention not to overdo with their attacks.

They can fade from this plane of reality, avoiding material forms of damages and they can also see with their eyes closed. Their eyes are likely of a bright yellow as seen in game: the legends surrounding Ysera's eyes hint at the fact her eyes are unique even among her flight - hence other green dragons don't have rainbow eyes.

 As a last resort, they may disorient the enemy and in order to release spells and heal back, before fighting once more. In fact, they are excellent healers, much more so than their blue or black counterparts and may easily take on both the role of healer or damage dealer.

Their main weakness comes from corruption magic and similar attacks, such as the emerald nightmare and its corruptive force. One may argue that even arcane magic in its corruptive and twisted form can be quite of a nuisance!