Seed of Corruption

Seed of Corruption, often abbreviated SoC, is a warlock Shadow-based Damage over Time spell that does Area of Effect Direct Damage after the target receives a specific amount of damage. This spell was introduced in The Burning Crusade expansion.

Tips and tactics
In instances, chain-casting this on a single target that is taking heavy damage from other sources will ensure each cast detonates before the next one lands. If used with Soulburn via affliction talents, don't spread Seed of Corruption around on each target following the Soulburned detonation, as the Seeds will remove the spread Corruption DoTs. Seed of Corruption also works particularly well in conjunction with Shadowflame. Cast Seeds on several targets, then Shadowflame the group to instantly detonate all of the Seeds for a powerful burst of AoE damage, plus the DoT from Shadowflame and possible Corruption of you used Soulburn.

While soloing, Seed of Corruption is most useful while in situations where you have to deal with multiple mobs at the same time and you have a Voidwalker out. As soon as the Voidwalker grabs aggro, quickly cast SoC on as many mobs as you can, trying to avoid the target your Voidwalker is directly attacking to avoid a premature detonation. If all goes well, detonations will wipe all mobs in a single wave. If you can't kill all of them with the initial round of detonations, you'll have a pack of very angry mobs at half-health beating on you and you won't be able to do anything.

If you have a competent AoE tank, this spell can be used to quickly clear large groups of mobs, especially if there are other DPS contributing AoE damage. This tactic can clear lower level dungeons incredibly quickly (particularly with affliction warlocks, who bring low downtime and high shadow damage to the equation).

Seed of Corruption is best used when you don't have aggro. It's difficult to cast a 2-second spell while taking damage from multiple mobs. If you have mobs attacking you already, you're better off using Hellfire over SoC.

In PvP, it can be useful to steadily cast it at a target which constantly takes damage, as the previous SoC can trigger before the next one arrives; this can be used to deal immense amounts of damage in short time. It can also be cast on pets, and if you can get the pet close to the owner when it detonates, it can provide additional damage to its owner. In large group PvP, casting it on random targets in the group can cause significant amounts of damage, particularly if the targets are taking damage from other sources, ensuring the Seeds will detonate too quickly to be cleansed.