Mana Burn

Mana Burn
Mana Burn 3 sec cast 30 yd range 14% of base mana Destroy 10% of the target's mana (up to a maximum of 20% of your own maximum mana). For each mana destroyed in this way, the target takes 0.5 Shadow damage.
Usable by
Class	Priest
Properties
Type	Offensive
School	Shadow
Cooldown	None/Global Cooldown
Talents
Improvement talents	Improved Mana Burn

Mana Burn is a Shadow-based Priest spell. It drains mana from the enemy, causing Shadow damage.

Rank table

Rank	Level	Type	Mana cost	Cast time	Mana burned	Cost
1	24	Discipline	14% base mana	3 seconds	10% of the target's mana (up to a maximum of 20% of your own maximum mana)	50

Mana Burn will destroy 10% of the target's mana. If the actual amount is greater than 20% of your maximum mana, it will destroy only an amount of 20% of your maximum mana. This is necessary to prevent Mana Burn from destroying too much mana on enemies with a very large mana pool.
Mana Burn will instantly break Fear, Hex and Psychic Scream.
Mana Burn has some strange behaviour in combination with the Shadow tree. It works with Shadow Weaving, Shadowform, Vampiric Embrace, and Vampiric Touch. It does benefit from Darkness and Shadow Affinity. Shadow Focus probably does not affect it, though.
Its threat simply depends on its damage and follows normal rules; the mana drain does not cause any additional threat.
Shadowform will increase damage done by this spell.

Improved Mana Burn reduces the casting time of Mana Burn.
Force of Will increases spell damage and critical strike chance for all offensive spells.

Mana Burn is useful both in PvE and PvP. It can be used against enemy spell casters in PvE to prevent them from casting their spells, especially healing spells. In PvP this spell is helpful against healing classes.
With Improved Mana Burn, its effectiveness can be raised enormously. In addition, its susceptibility to interrupt effects can be reduced.
Combined with a shadow spec'd priest's Vampiric Embrace, Mana Burn can be an amusing and effective way to use the target's mana to heal your party (while damaging them in the process). Adding the Shadow spec Vampiric Touch to this also allows your mana to be somewhat replenished in the process.

Hotfix (2009-04-30): "Mana Burn has been reduced to 10% mana burned (up to a maximum of 20% of the Priests mana), down from 13% (max 26%). ^[1]"
Hotfix (2009-04-30): "Mana Burn now causes Fear, Hex and Psychic Scream to break early when used. ^[1]"
Patch 3.0.8 (2009-01-20): Now burns a percentage of maximum mana, only one rank remains.