Insect Swarm

Insect Swarm
Insect Swarm Instant cast 30 yds. range 8% of base mana The enemy target is swarmed by insects, decreasing their chance to hit with melee and ranged attacks by 3% and causing X Nature damage over 12 sec.
Usable by
Class	Druid
Properties
Type	Offensive and Utility
School	Nature
Cooldown	None/Global Cooldown
Talents
Talented	Yes
Talent tree	Balance, Tier 3
Other information
Ranks	7
Related debuff
Magic Insect Swarm Chance to hit with melee and ranged attacks decreased by 3% and {X/6} Nature damage every 2 sec. Duration: 12 sec.

Insect Swarm is a talent-learned DoT spell and debuff.

Rank table

Rank	Level	Mana Cost	Damage	Training Cost
1	30	9% base mana	144	Talent
2	30	9% base mana	234	60
3	40	9% base mana	375	1 40
4	50	9% base mana	540	1 20
5	60	9% base mana	744	3 40
6	70	8% base mana	1032	20
7	80	8% base mana	1290	20

Does not stack with chance to miss % of other insect swarm.
Unlike a lot of other DoT spells which deals damage every 3 seconds, Insect Swarm deals damage every 2 seconds, meaning 6 ticks will occur in its duration of 12 seconds, 7 if you have Nature's Splendor.

Glyph of Insect Swarm increases the damage of your Insect Swarm ability by 30% but it no longer affects your victim's chance to hit.

The talent is useful when used in conjunction with Moonfire. In addition, it's a cheap DoT that gains 120% from your +spell damage, which makes it desirable for certain balance builds, making it one of the most mana efficient DoTs in the game.
In a raiding perspective the damage mitigation with the chance to miss helps with the survival of the main tank.
Unlike most (all?) Druid spells, Insect Swarm does not interrupt the swing timer. http://forums.worldofwarcraft.com/thread.html?topicId=2509262193&sid=1

Patch 3.1.0 (2009-04-14): The bonus damage from spell power on this damage-over-time ability has been increased significantly to match similar spells on other classes (from 76% to 120%).
Patch 3.0.3 (2008-11-04): Tooltip corrected to indicate it does not affect hit chance with spells.