The Emerald Dragons are Lethon, Emeriss, Ysondre and Taerar. These dragons are world spawns located in Duskwood (Twilight Grove), the Hinterlands (Seradane), Feralas (Dream Bough), and Ashenvale (Bough Shadow). They are raid level difficulty. However, some dragons are more challenging than others. Ysondre is considered to be the easiest.
All four dragons share the Sleep (summoning "Dream Fog"), Noxious Breath, Tail Sweep, Mark of Nature and Aura of Nature abilities. Each dragon also has a few unique abilities. One of these is considered the dragon's ace move, and will be performed when the dragon loses 25 ± 5% of its max life. In other words, the ace move will only be performed three times; when the dragon is at 25%, 50%, and 75% life. When it is performed, the dragon will also yell something.
Used by all the Dragons of Nightmare
Seeping Fog - Summons two clouds of Dream Fog that will chase random players around the dragon and put them to sleep for 4 seconds.
Noxious Breath - Deals 3000 Nature damage and applies a 30 second DoT that increases cooldowns on all abilities by 10 seconds and inflicting 350 to 450 Nature damage every 3 seconds. The DoT can stack up to 6 times. The main tank should be the only one affected by this.
Tail Sweep - Inflicts 925 to 1075 damage on enemies in a 30 yards cone behind the dragon, knocking them back.
Summon Player - Teleports the player who has the most aggro in front of the dragon if the player tries to run out of combat. This ability has first been noted after patch 2.0.1.
Mark of Nature - If players are killed by a nightmare dragon, they will be afflicted by a 15 minute debuff called Mark of Nature. If engaging the dragon during this time, they will be slept for 2 minutes rather than 4 seconds as with the Dream Fog.
Aura of Nature - A invisible pulsing aura that interrupts actions like eating, drinking and bandaging when close to the dragon. Will trigger the 2 minute sleep when combined with Mark of Nature.
All the Dragons of Nightmare are also immune to nature damage.
As with all raid boss encounters, bringing lots of consumables for long fights is mandatory. Having a couple stacks of NR for these dragons is also very important. However, for Lethon, bring shadow protection as well. As always, bandages on ALL players is also very key!
congrats on C'Thun guys!