Debuffer

There are two variants of debuffers: With Blight or without Blight.

Passive skills
Rain Dance increases chance to land debuffs. You can either spend 1 point or 20 points into this skill. If you spend 1 point, it means you will focus on a single skill, such as Hold or Shout. If you put many points, it means you will be a swiss army knife, having different debuffs for different enemies, but you will not be able to use debuffs whose level matters, such as Insulation.

Phantom Power increases duration of debuffs. As a debuffer, you will want to max this out to get as much duration as possible. This has to be done because all monsters have disable protection for 14 seconds whenever they are subjected to a disable.

Blight lets you cast buffs on enemies with reverse effect. The downside to this is that buffs, unlike debuffs, rely on your skill level for their effect. For example, Insulation would decrease elemental resistances depending on spell level, while Hex would simply disarm. You are either disarmed or not but the effect if blighted Insulation depends on your skill level in Insulation. This means Blight builds are skill point intense.

Without blight
Hex, Silence, Shout and Stunning Attack and Disarm are pure disables, temporarily stopping enemies from doing anything at all. Just keep track of whether the enemy needs to be disarmed or silenced.

Hold and Cripple are weaker disables but they add a short extra duration.

With blight
These buffs are options:
 * Song of Fire can decrease enemy attack speed, similar to Devotion.
 * Stoneskin, Hallow and Insulation can decrease resistances to minimum, similar to Gloom. This is good against enemies with high resistances but does little against enemies with low resistances.

Party buffs, such as Battle Roar and War Cry, do not work with Blight. Only single-target buffs work.