Avenger

Avengers are warriors with conviction. A church has Paladins to be their army and fight the enemies of their cause. They have Clerics to examplify their teachings and spread them through the land. But every church has their secrets, their old rites, their dealings that are a little too shady to be in the public eye. That's where the Avengers come in. 

Avengers are a mix of 'holy rogues' that handle the more secret missions for the church, and Internal Affairs that handle delicate situations inside the church itself. Each god and church has their own way of handling their Avenger order compared to their Paladin and Cleric orders. Some churches might keep the Avengers a secret from the public eye, or even from other members of the church and make it a full-on secret society within the church. Other churches might have them fully in the public eye, either as a deterrent to evildoers or as a way to promote transparency. Some churches dedicate their Avenger orders to one specific task (i.e. hunting undead or retrieving stolen relics), but most Avengers are generalists that get a lot of freedom in how to handle their assignments (for example, by teaming up with an adventuring party). 

Avengers don't wear armour, and can track and hunt down a specific target. Their powers are based on movement and damage. They also get to pick one weapon (usually their deity's favored weapon) that counts as a Monk weapon for their attacks. 

This is based on the Way of the Avenger by (I think) someone called Samuel on the internet. It recreates the basic mechanics and feel of the 4E Avenger class from Complete Divine. It's somewhat like a 'Divine Rogue'. In 5E this is reimagined as a monk subclass.

Implement of Vengeance

You can choose to gain proficiency with one melee martial weapon of your choice. This weapon counts as a monk weapon for your monk class features, and you can choose to use either its damage dice or your Martial Arts die for damage rolls made with the weapon.

Censure of Pursuit

You can use a bonus action to place a censure on a creature that you can see within 30 feet of you. The censure lasts for 10 minutes, or until you fall unconscious, or the creature dies. Until the censure ends, you gain advantage on the first attack roll you make against that creature each turn, and you know the distance and in what direction that creature is from you. You may have only one creature censured in this way, with any new censure replacing and ending an already existing one. You may use this feature a number of times equal to your Wisdom modifier, regaining all uses when you complete a long rest.

Divine Retribution

Starting at 6th level, once per turn when you hit a creature that is censured by you with a Monk weapon or unarmed attack, you can spend up to a number of Ki Points equal to your Wisdom modifier to deal additional radiant damage. This damage is equal to 1 Martial Arts die per Ki Point spent this way + your Wisdom modifier.

Pursuit of Trespassers

Starting at 11th level, you can spend 3 Ki points as an action to take on an ethereal form which lasts for 10 minutes, or until you end the form as a free action or fall unconscious.

In ethereal form, your movement speed is increased by 20 and you gain flying speed equal to your movement speed.

While ethereal, you can move through objects and other creatures as though they were difficult terrain. If you end your turn inside an object, you take 1d10 force damage. If the ethereal form ends while you are inside an object, you are forcefully expelled to the nearest unoccupied space outside the object, and you take 1d10 force damage for every 10 feet you are forcefully moved by this expulsion. This damage cannot be prevented or reduced in any way.

Judgment

Starting at 17th level, when you hit a creature with an attack made with the type of weapon you chose for your Implement of Vengeance feature, you may spend 5 ki points to cast Banishment as a 4th level spell targeting that creature as a bonus action, requiring no components, concentration, or spell slot. When you cast the spell in this way, the creature is always banished to a harmless demiplane and returns when the spell ends, regardless of what its natural home plane may be.

At the start of each of your turns while you have a creature banished in this way, the creature is subject to your Divine Retribution, taking radiant damage as if you’d spent the maximum number of Ki Points allowed with that feature. The spell ends early if the banished creature dies while it is banished.