- Remove a chosen monster in the dungeon hall to the bottom of the dungeon deck, then re-populating the hall as normal
- Choose to rearrange the currently revealed monsters to either help or hinder players in getting past darkness to combat these monsters.
As an added cost to doing either of these actions the player using Banish must destroy a card from their current hand, followed by drawing another one from their deck as a replacement.
The destroy effect must be done before drawing another card.
Banish is one of the cards that is meant to be removed from the game when the solo variant is used, as its power tends to destroy the balance of monsters attacking the village and in the challenge of monsters being at certain ranks in the dungeon.
Official Glossary entry from 1.4 Rules
You must declare you are entering the Dungeon to play Banish, but do not choose which Monster to attack until after the Hall is refilled. If Banish results in a Breach (or Trap) Effect, resolve it immediately. You may rearrange the hall so as to place the Thunderstone in Rank 1 of the Dungeon Hall, ending the game immediately without collecting the Thunderstone. Multiple Banish cards can be used before choosing which Monster to attack, but each must be completely resolved before the next can be played. You must draw a card when using this Dungeon Ability.