Avenger

The Avenger is a Dungeons & Dragons class concept which has appeared from BECMI, through Advanced Dungeons & Dragons and to Dungeons & Dragons 4th Edition, across three different settings. The original version is tied into the Mystara setting, the second to the Ravenloft setting, and the third version is tied into the Nentir Vale setting. Each is a very different beast.

Mystara Avenger

This BECMI class is actually a kind of prototype for Prestige Classes; it is the Chaotic counterpart to the Paladin and Knight, and represents a special upgrade that a 9th level Chaotic alignment Fighter can undergo by swearing an oath of allegiance to a Chaotic church - if he refuses a call for aid by this church, he loses his Avenger powers, though he can regain them by finding a new church to swear himself to. He gains the ability to Detect Evil and, if his Wisdom is 13+, cast Cleric spells as if he were a cleric with a level equal to 1/3rd his fighter. He can also attempt to Charm Undead (functions as per Turn Undead, with effective cleric level equalling 1/3rd his Fighter level), and whilst he can't have human or demihuman hirelings, he can attempt to "persuade" Chaotic-aligned monsters to travel with him. This functions as an at-will Charm Monster ability, and back in BECMI, depending on the creature's intelligence, this could leave the monster under his command for months or even years, depending on the dice and how the player treated this pseudo-hireling.

Basically, this was your prototype Blackguard, but with less mandated evil behavior..

Ravenloft Avenger

The Avengers of the Demiplane of Dread were a "Warrior" type class introduced in the AD&D sourcebook "Domains of Dread", which was the third and final "campaign setting" equivalent for Ravenloft under TSR, the first to be set post-Grim Requiem, and the first to be a single massive book rather than a whole boxed set.

The Avenger of AD&D is one of four "setting appropriate" classes added to the game in "Domains of Dread", the PC & DM's expansion book for Ravenloft, alongside its contemporaries the Arcanist, the Anchorite and the Gypsy. Unfortunately, it suffered the curse that bedeviled Ravenloft player-focused content of AD&D (indeed, some would say of any D&D edition), a little weakened by the rule system version of the Paladin, yet good to roleplay.

Requiring Strength 15, Dexterity 14 and Constitution 15 to qualify for, the Avenger was DoD's thematic replacement for the Paladin (with a dash of Ranger); a warrior fixated upon a single nemesis figure, both individually and in general. Essentially, they're AD&D Fighters with the following tweaks:

• Cannot be Lawful aligned, which is obvious, since his goal is to kill his nemesis, not to become someone else's pawn.
• Cannot specialize in Ranged Weapons.
• Do not establish Holdings.
• Do not attract followers.
• +5 hit points when fighting an enemy that "reminds them of their nemesis" in close combat.
• +10 hit points when fighting their nemesis in close combat.
• Can intuit which direction to go in order to pursue their nemesis by making a successful Wisdom check.

This Fighter variant is using the Paladin's experience table.

In 3rd edition, Sword & Sorcery brought the idea back as a Prestige Class in "Van Richten's Arsenal". Now a kind of "uber-Ranger", the Nemesis retained its original fluff as an individual driven to pursue the destruction of a singular Nemesis, and was consequently still a very one-trick pony class concept. To qualify as an Avenger in 3e, you need to be Non-Lawful in Alignment, have a Base Attack Bonus of +3, two specific Feats (Endurance and Jaded), 2 ranks in the Gather Information Skill, and 6 ranks in the Sense Motive skill. Finally, you have to have suffered some disaster at the hands of a foe who subsequently escaped punishment; this is your Nemesis, and they are literally the defining focus of this class. If you ever lose your Nemesis, you can't progress any further in the prestige class.

The Avenger's class skills all tie into its Man-Hunter theme; Craft (for traps), Escape Artist (for getting out of Nemesis traps), Gather Information, Hide, Intimidate, Listen, Move Silently, Profession, Search, Sense Motive, and Spot. If their Nemesis is a kind of supernatural creature, than an avenger also treats the branch of Knowledge (Monster Lore) relating to that Nemesis' type as a class skill - for example, if your Nemesis is Strahd von Zarovich, you have a knack for Knowledge (Vampire Lore). Not that it matters much, because an Avenger is hardly a skill monkey; 2 + Int modifier skill points per level is all they get. Which just goes to show how borked up the Skills system could get in 3e...

What an Avenger is, however, is a beat-stick. Their Base Attack Bonus increases by +1 per level, and they have strong (+2 at first level, +7 at 10th level) Fort and Will saves, if somewhat shoddy Reflex saves (+1 at 3rd level to +3 at 9th). They're proficient in all Simple & Martial Weapons, Shields, and all types of Armor.

The only class features that an Avenger gets in 3e are Intuition and Resolve, both of which are Extraordinary Abilities. Intuition lets them make a Sense Motive check against a DC imposed by their Avenger levels (DC 20 at Avenger 1, DC 12 by Avenger 9) once per day; if they succeed, they are clued into the general direction they need to go in order to find their Nemesis; the better they do on this check (in variables of 5), the more precisely they can pinpoint where their target is, from a city-sized area (beat the check by 5) to a specific neighborhood (beat the check by 10) to specific locales within that neighborhood (beat the check by 15). Resolve, on the other hand, gives them a morale bonus to Constitution and Wisdom determined by their Avenger level (+2 at 2nd, +4 at 4th, +6 at 6th, +8 at 8th and +10 at 10th) when fighting their Nemesis - at 6th level, they also get a weaker version that applies when fighting their Nemesis' minions or opponents who strongly remind them of their Nemesis; the example given is that an Avenger seeking a werewolf Nemesis would gain this lesser bonus (+2/4/6 at levels 6/8/10) when fighting any werewolf.

All in all, it's not... bad, per say, it's just very one-dimensional. It has one trick it does, and it does it well, but that's all it does. At the very least it doesn't cripple you the way taking the Avenger class in AD&D did (remember those pesky multiclassing rules, or lack thereof?), but it's still only useful if your DM wants to set up a specific "arch enemy" kind of campaign.

3.5 Avenger

Introduced in an April Fools article by Wizards of the Coast. Literally just a variant of Assassin without the need to be evil.

Nentir Vale Avenger

A Tiefling Dread Imperator, an Avenger who seeks to reunite the splinted faiths of old Bael Turath.

Avengers in the Nentir Vale setting of 4th edition are a class introduced in the Player's Handbook 2. Since Paladins can no longer fall, Avengers are the answer to renegades and heretics. Assassins for their clergy, Avengers hunt down enemies of their god and kill them with great prejudice. They do this by swearing an Oath of Enmity upon their target, which basically means they hate the person to death. This comes in three flavors. The first makes your attacks stronger if the enemy tries to run away. The second makes your attacks stronger if the enemies allies try attacking you to save their buddy you just swore to kill. The third makes your attacks stronger if you have allies attacking the same enemy. Also, if you have no other enemies adjacent to you, you can roll two attack rolls and pick the better one, making for delicious crit-fishing.

However, Avengers are considered to be one of the weaker classes, mainly because their big key power, the Oath, doesn't work if you have more than one enemy adjacent to you. Additionally, the DM can easily make the first two oaths useless by not having the enemy you're targeting run away, and not having other enemies attack you while you're smiting.

An avenger works best when used as an aide to a defender or the other strikers. This is because they have a great deal of abilities that allow for moving the enemies where the avenger or his buddies need them, but is less powerful on the direct damage front. Use them as a support and to remove any enemies that are attacking the party rangers.

Absorbed into the Paladin class in 5e, as the Oath of Vengeance Paladin, and his "roll 2d20 and keep one" shtick now forms the core of the "advantage" system..