Thorns

Thorns is a druid buff spell that can be cast on yourself and friendly players. Any time a target affected by Thorns is hit in melee, the attacker takes nature damage.

Related Glyphs
Glyph of Thorns is a major glyph that reduces the cooldown of thorns by 20 seconds. If managed properly, the downtime of thorns would be only ~5 seconds. Thus this is an excellent option for a major glyph slot if there is constant incoming melee damage.

Tips and tactics

 * Cast Thorns on tanks to help them keep aggro on multiple enemies. Always keep Thorns up on yourself when you are tanking to provide some additional threat.
 * You generally should not cast this on casters while in a group, as the damage caused by Thorns does increase aggro, making it harder for others to pull mobs off them.
 * Thorns will act as a buffer against dispels in PvP, giving enemies a chance to dispel your Thorns instead of some more important buff.
 * The damage caused by Thorns can, due to lag, sometimes break crowd control effects like Hibernate and Polymorph. Because of this, if you or someone in your party has latency of over 500, you may want to avoid using Thorns if you are using any in-combat crowd control.
 * Thorns can be very useful when being attacked by an enemy that has very low health as they will often die quickly from the Thorns damage without requiring your attention. Many creatures summon minions that have few hit points - Thorns will effectively dispatch these enemies for you.
 * As Thorns benefits from your spell power at the time of casting, you can activate any trinkets that increase spell power and equip items with high spell power before casting it to maximize the effect.

Refreshing and Spell Power
When refreshing Thorns on yourself, you may sometimes get the error message, 'A more powerful spell is already active.' This is understandable if the initial buff was cast by a different druid with a higher rank of the spell or talents to increase its potency, but may be confusing when it was you who cast the spell. The reason for this error message is that Thorns benefits from the druid's spell power at the time it was cast, not at the time of the hit. Thus, casting Thorns on yourself while at a higher spell damage (such as with a trinket activated) will make it impossible to refresh the buff without first right-clicking it off if your spell power has dropped down. Some buffs and items may temporarily increase spell power, causing this to occur. If using similar items or abilities with short cooldowns, it would be best to max out spell power before casting Thorns to get the maximum effect out of it.