Tosses the enemy target into the air, disorienting them but making them invulnerable for up to 6 sec. Only one target can be affected by your Cyclone at a time.
Cyclone is a level 48 druid ability. It is very similar in mechanics to [Banish]: targets affected by Cyclone cannot move or perform any actions, are immune to receiving heals or buffs, and also completely immune to all incoming damage and unable to be debuffed. Cyclone is affected by diminishing returns, both in PvE and in PvP. Certain versions of this spell cast by monsters CAN be dispelled by [Mass Dispel]. Cyclone has no cooldown.
You can only Cyclone one target at a time. Cycloning a second target will cancel the one currently in effect.
Due to diminishing returns, you will have three successful casts on a single target before immunity begins. This spell's duration is cut in half every time, beginning with 6 seconds, dropping to 3 on the next use, and finally 1.5 seconds.
Any aura or passive buff granted by the affected player or mob to other players or mobs will be temporarily negated until the effect ends. For instance, if you cast Cyclone on a warlock's pet, [Soul Link] will be removed from the warlock and their pet until Cyclone's effect ends.
The target affected by Cyclone is also immune to HoT or DoT effects.
Tips and tactics
Cyclone can be tricky to use because in addition to the affected target being able to perform any actions, no actions may be performed upon the affected target. A Cyclone at the wrong time can cause another player to waste a long cooldown or a high cost spell, whereas a Cyclone at the right time may cause a player to stop casting a long or highly damage attack, or even cause them to not receive a large heal that was coming their way.
Cyclone can be only be used in humanoid and [Moonkin Form].
Although the Cycloned target is immune to all spells, this does not prevent you from casting spells on them; it will simply have no effect, and the time and mana spent casting will be wasted, as will any cooldowns used. This does however allow you, with a good sense of timing, to begin casting spells on the target in anticipation of the end of the Cyclone.
Using Cyclone as a long-term form of crowd control in an instance can be tricky and difficult for the druid to manage, especially if the druid is the healer. In most situations it is more effective to use [Entangling Roots] if it is necessary to crowd control on a large pull, or continuously throughout an instance. If the target that must be controlled is a ranged attacker however, then Cyclone becomes especially useful.
When using this spell in situations where you're with others, grief can be avoided by communicating how long you will be Cycloning, and when it has gone onto diminishing returns.
Most city raids are always wary of a Cyclone coming down on the tank that has the boss, as the boss will suddenly go after someone squishy.
Patch changes
Patch 9.0.1 (2020-10-13): Now an ability available to all druids
Patch 8.1.5 (2019-03-12): Mana cost reduced by 33%.
Patch 8.0.1 (2018-07-17): Converted to a PvP talent (was a rank 6 honor talent).
Hotfix (2017-06-15):Cyclone should now work correctly on all tamed Hunter pets.
Hotfix (2016-08-26):Cyclone cast time reduced to 1.7 seconds (was 2.0 seconds).
Patch 7.0.3 (2016-07-19): Now an honor talent for Balance and Restoration druids.
Cyclone now shares Diminishing Returns with Fears, and can be canceled by immunity effects (i.e. Divine Shield, Ice Block, etc.), and can be dispelled by Mass Dispel.
Nature's Swiftness can no longer turn Cyclone into an instant-cast spell.
Patch 5.4.0 (2013-09-10): No longer has a 20-second cooldown for Feral Druids.
Patch 5.2.0 (2013-03-05): Now has a 20-second cooldown for Feral Druids.
Patch 3.2.0 (2009-08-04): Victims of Cyclone can no longer receive healing from health drain effects such as [Devouring Plague] while they are affected by Cyclone.
Patch 2.4.0 (2008-03-25): Range has been reduced from 30 yards down to 20 yards.
It is no longer possible to Cyclone two targets at the same time in the outdoor world.
Paladin Auras, [Trueshot Aura], and [Aspect of the Pack] will now be automatically reactivated when Cyclone wears off of a victim who had one of the abilities active.
Visual spell effect changed. Undocumented.
Patch 2.1.0 (2007-05-22): This ability will no longer work on hunters with The Beast Within active or hunter pets with Bestial Wrath active.
[Cyclone].
[Banish]: targets affected by Cyclone cannot move or perform any actions, are immune to receiving heals or buffs, and also completely immune to all incoming damage and unable to be debuffed. Cyclone is affected by diminishing returns, both in PvE and in PvP. Certain versions of this spell cast by monsters CAN be dispelled by 
[Mass Dispel]. Cyclone has no cooldown.
[Every Man for Himself], 
