The Overlord player uses Overlord cards to perform various abilities, such as benefiting monsters or springing a trap on the heroes. There are both basic Overlord cards, which the overlord player begins the game with, as well as upgrade cards, which he can purchase with experience points when playing the campaign.
During gameplay the Overlord deck must always have at least 15 cards in it. The Overlord deck begins a campaign with the fifteen Basic 0 level cards. Further cards can be purchased using experience points as the campaign progresses. As new cards are purchased they can be added and removed from the overlord decks between quests (but not in between a quest with two encounters. The Overlord can customize which cards available to them are available in their deck as long as they always have a minimum of 15 cards in their deck at the beginning of a quest. If the Overlord draws the last card in their deck the discard pile is shuffled and turned into a new draw pile for them. The Overlord draws one card at the beginning of their turn and have no maximum hand size.
There are three original classes of upgraded Overlord cards; Warlord, Saboteur, and Magus. In addition to this there were four Universal Level 1 cards included in the base game that are available for purchase at any time. Then, each expansion brought new cards:
- Punisher was added with Lair of the Wyrm
- A second set of beginning cards called "Basic II" cards were added with Labyrinth of Ruin rather than a full new class
- Infector was added with The Trollfens
- Shadowmancer was added with Shadow of Nerekhall
- Enchanter and Unkindness was added with Manor of Ravens
Within each class, there are three levels of cards available. Level 1 cards cost one experience point, level 2 cards cost two experience points, and level 3 cards cost three experience points. Level 1 cards are always available for the overlord player to purchase. In order to purchase a level 2 card, the overlord player must first currently have two Level 1 cards of that class in his deck. He must have three cards of a class in his deck (which can be any combination of Level 1 and Level 2 cards) before purchasing a level 3 card of that class. Unlike heroes, the overlord may purchase cards from multiple classes. Universal cards are always available for purchase.
In the base game, there are 4 universal cards each worth 1 experience point and each class has 4 level one cards, 2 level two cards, and 1 level three card in addition of the 3 basic classes.
There are 15 Basic Overlord Cards that the overlord player plays with in a non-campaign game. These are also the same cards the overlord player receives at the beginning of a campaign. These cards provide basic bonuses and traps.
- 2x Dark Might
- 2x Tripwire
- 2x Dash
- 2x Frenzy
- 2x Dark Fortune
- Pit Trap
- Critical Blow
- Poison Dart
- Word of Misery
- Dark Charm
Instead of the regular 15 basic cards, the Overlord player may choose 15 basic II cards introduced in the Labyrinth of Ruin expansion. These are not level 2 cards that cost 2 experience points to purchase, but instead an alternate set of Basic cards called "Basic II".
- 2x Uncontrolled Power
- 2x Befuddle
- 2x Dirty Fighting
- 2x Blinding Speed
- Grease Trap
- Mental Error
- Reflective Ward
- Sign of Weakness
There are 4 (2 more in Labyrinth of Ruin, 5 more in Shadow of Nerekhall) Universal Overlord Cards that the overlord player can spend experience points on after each quest. Each cost one experience. The abilities provided are general such as re-ordering the top cards of the deck, searching your deck, or healing a monster.
- 2x Plan Ahead
- 2x Dark Remedy (Labyrinth of Ruin)
- Dark Resilience
- Placebo (Shadow of Nerekhall)
- Solidarity (Shadow of Nerekhall)
- Upgrade (Shadow of Nerekhall)
- Refresh (Shadow of Nerekhall)
- Diverse Means (Shadow of Nerekhall)
Overlord Reward type cards were introduced beginning with the Lair of the Wyrm expansion and may be gained without spending any experience points, but only when the Overlord player wins specific Rumors or Quests.
- The Wyrm Queen's Favor (Obtained by winning the Armed to the Teeth quest in the Lair of the Wyrm)
- Splig's Revenge (Gathering Foretold quest in the Labyrinth of Ruin)
- Twin Souls (Fire and Brimstone quest in the Labyrinth of Ruin)
- Offertory Affliction (Obtained by a secondary objective in the Three Heads, One Mind quest of the Trollfens)
- Secrets of Flesh (Obtained by a secondary objective in the Ghost Town quest of the Trollfens)
- Toxic Reprisal (Obtained by a secondary objective in the Food for Worms quest of the Trollfens)
- Endless Supply (Obtained through one of the Manor of Ravens quests.)
- Unseen Wings (Obtained by winning the first of two quests in the Oath of the Outcast expansion)
- Fire Gems (Obtained through one of the Crown of Destiny quests)
- Forgotten Sorcery (Obtained by winning the Shadowside Watch in the Crusade of the Forgotten quests)
- Power in Numbers (Obtained through one of the Guardians of Deephall quests)
- Hard Knocks (Obtained through one of the Visions of Dawn quests)
- Hunk of Junk (Obtained through one of the Bonds of the Wild quests)
There are 7 Overlord Cards in the Warlord class. 4 level one, 2 level two, and 1 level three. The Warlord class focuses on creating more deadly monsters by giving them extra armor, more damage, multiple attacks, bonuses for defeating heroes, and allowing the overlord to spawn additional monsters. Each of the Warlord cards is an event type.
There are 7 Overlord Cards in the Magus class. 4 level one, 2 level two, and 1 level three. The Magus class provides cards that allow the overlord player to draw extra cards, use a dead monster, deal wounds directly to a hero, and force heroes to suffer additional fatigue. Each of the Magus cards is a magic type.
There are 7 Overlord Cards in the Saboteur class. 4 level one, 2 level two, and 1 level three. Each of the Saboteur cards is a trap that is triggered by something the hero does. The traps can add conditions, force rerolls, transform heroes into monkeys, and even force a hero to be defeated.
There are 7 Overlord Cards in the Punisher class introduced in the Lair of the Wyrm expansion. 4 level one, 2 level two, and 1 level three. Punisher specializes in making heroes pay for every inch they advance. In addition, heroes may also be punished for attacking monsters or healing.
There are 7 Overlord Cards in the Infector class introduced in The Trollfens expansion. 4 level one, 2 level two and 1 level three. The Infector specializes in 'infecting' the heroes with special Overlord tokens to represent the infection. The infection tokens can be spent by the Overlord in various situations for bonuses.
There are 7 Overlord Cards in the Shadowmancer class introduced in the Shadow of Nerekhall expansion. 4 level one, 2 level two, and 1 level three. The Shadowmancer forces the heroes apart, potentially turning them against each other and forcing them to split up.
There are 7 Overlord Cards in the Enchanter class introduced in the Manor of Ravens expansion. 4 level one, 2 level two and 1 level three. The Enchanter specializes in boosting entire groups of monster with special lasting effects.
- Elixir of Stone
- Wristlet of Wind
- Dragonbone Pendant
- Rings of Zhol'alam
- Rune of the Phoenix
- Ward of Peace
- Sign of the Last Zenith
There are 8 Overlord Cards in the Unkindness class introduced in the Manor of Ravens expansion. 4 level one, 3 level two and 1 level three. The Unkindness specializes in a Raven Flock that is always active once bought. He can use his cards to interact with that special flock, some kind of familiar, called Servant, for the Overlord.