There are X (VALUE UNKNOWN) runes in the game.

Sahasrara (boss fight!): Edit

Teleports you to the endroom of the floor. If the floor doesn't have a boss you'll be faced with a random boss. After beating it you'll get an item and proceed as normal.

Manipura (golden rain): Edit

Gives 195 gold.

Anahata (regeneration): Edit

Fills your health and mana.

Ajna (map opened): Edit

Reveals the floor layout.