The Harbinger is a melee Wilder class that has mostly passive talents and does not use resources for any of its class talents. It has a lot of "proc" damage and is excellent at killing dense groups of enemies, but doesn't have a lot of debuffs and its mobility isn't the best.
The focus is on positioning tactics and on character building strategy (many competing passive talents). The focus is obviously not on complex talent rotations or resource management.
Unlike Runic Golem, this addon is not a joke. It's a serious class that I think fits in the game.
It has 8 new talent categories, plus Combat Training, Staff Combat, and Mindstar Mastery all unlocked at 1.30, and of course, Survival locked at 1.00.
You can make a reasonable case for all three weapon types on this class; conventional weapons have the best weapon damage as usual, but mindstars let you ignore Strength and staves have the procs damage bonus. Harbinger starts with Staff Combat and Mindstar Mastery unlocked for the purpose of player convenience, even though they use resources. (It does not start with a mana pool, so you can still go antimagic, just don't put points in Channel Staff.)
A sampling of talents:

A snowstorm follows you wherever you go. Every time you hit with a melee attack, you channel the storm's power through your weapon, creating a range 10 piercing beam of frost dealing X cold damage to all in its path, including the original target. Mental criticals apply.
The beam will only harm hostile creatures.
If you are wielding two weapons, this will only happen on 50% of attacks. Shields do not count as weapons.
The damage will increase with your Mindpower.

Every time you critically strike, the fire around you suddenly flares, doing X fire damage to all foes in a radius of 2 around you.
This only harms hostile creatures.
Physical, mental, and spell criticals will all trigger this effect.
The damage will increase with your Mindpower.

Removes up to X temporary detrimental effects, but also removes an equal number of temporary beneficial effects. If there are no beneficial effects remaining, no more detrimental effects will be removed.
Afterwards, you are healed by Y for each pair of effects that was removed. Mental criticals apply to the healing.
The healing will increase with your Mindpower.
This talent will not deactivate sustains.

The winds around you are so strong that they interfere with your foes' attacks. Your Defense increases by X, and all critical hits against you have Y% subtracted from their critical multiplier (but always do at least normal damage).
The Defense bonus will increase with your Mindpower.
Note: unlike Indiscernible Anatomy, this talent actually does what it claims to do.

When you hit with a melee attack, you get similar melee attacks against all foes connected to the one you just hit. This can affect any number of foes as long as there are no gaps between them, but will not hit the same foe twice. Only hostile creatures will be attacked.
Learning this talent grants immunity to melee retaliation damage.
Additionally, all lightning damage you deal is increased by X%.
Changes that may happen
- Obviously: bug fixes, balance tweaks, particle/icon tweaks, etc.
- Maybe slightly more active talents or talent categories.
- Changing/removing/replacing talents
- Somehow opening the class to undead (unlike other Wilder classes there's no thematic reason undead can't be Harbingers, but taking is_nature off of the talents would make the class unable to utilize talent on nature hit, so I don't really want to do that).
Changes that will not happen
- Adding lots of active talents
- Adding resource usage
- Converting the passives into sustains (yes I know radiant horrors exist, no they're not unkillable).
Criticism welcome. I've played a full game with Harbinger so hopefully there are no game-breaking bugs. Balance is very much open to change; in particular the class's single-target damage is likely too high.