The Banned Cards

The ban list has 13 cards. It must always have 13 banned cards. If a new card gets banned, it means some other card got unbanned. Cards only get banned when they attack a foundation of the game. Being powerful is not enough to get banned, it must deeply break the game. If the card is not banned it is free. There is no restricted list, no splash ban. Cards are played using their latest version, all erratas included.

The Ban List

1. Calling the Storm: the game is not stupid.
   
2. Accursed Summoning: the game is played with cards that are in your deck, or your opponent's deck.
   
3. Oni Tyrant: the game is played with cards that are in your deck, or your opponent's deck.
4. Enlightenment: the game is won via honor, dishonor, or conquest. 
5. Scouted Terrain: a conquest victory requires breaking 4 or more provinces.
6. Jurōjin's Curse: a round has one fate phase, and players alternate being first player.
   
7. Slovenly Scavenger: obsidian decks operate with restricted resources. Recursion is not a problem on its own, but neutral easy recursion is a problem.
8. Policy Debate: In a format where all cards are already restricted to 2 copies, having them vulnerable to direct discard through a Neutral event makes the usage of focused anti-something effects unfeasible. That ends up removing a whole layer of the game and meta game, making the game less deep.
   
9. Daidoji Uji 2: obsidian balances its larger access to powerful cards with the lower consistency of getting them. Uji's unrestricted deck search goes against this core pillar of Obsidian.
   
10. Lost Papers: the game is won through a mix of skill and luck, with skill being favored. Lost Papers flips the equation in favor of luck.
11. Contested Countryside: provinces form the backbone of a deck. Subverting or negating provinces is not a problem on its own, but doing that with a free recurring neutral is a problem.
    
12. The Way of the Warrior:the game is played with resource management. Efficient cards are not a problem, but a card that is proactive, and reactive, and protective, and free, and neutral is a problem.
    
13. Duty: the game offers card plenty of draw during the draw phase, but it must cost honor as a balancing factor. Duty's draw phase usage is inexcusable.

 The Rotation Bans

On July 6th, 2022, the Emerald Legacy released Restoration of Balance. This whole expansion is not valid in Obsidian.

Restoration of Balance is an expansion focused on replacing a few cards with new versions of their effects. However, in Obsidian having 2x max copies of each card is a fundamental rule, so we cannot maintain both the original and the re-released version of cards valid in Obsidian. If we let them be valid, the 2x rule would be practically broken for a few cards.

The decision to keep the old cards instead of the new is taken to retain the vintage feel of Obsidian.