Undead•Spirit is a Level 2 class of monsters.
Ghost[]
Official Glossary entry from 1.4 Rules
If you do not have at least +1 Magic Attack, the total Attack Value is halved, round down. Reduced Strength can cause Weapons to become unequipped.
Haunt[]
Official Glossary entry from 1.4 Rules
Choose one Hero (and any equipped Weapon). All Light, Attack, and Magic Attack of that Hero (and Weapon) are reduced to 0. Militia are Heroes.
Revenant[]
Official Glossary entry from 1.4 Rules
You must have at least +1 Magic Attack in order to kill the Revenant. Heroes destroyed by the Revenant die at the end of the battle. Reduce Strength can cause Weapons to become unequipped.
Spectre[]
Official Glossary entry from 1.4 Rules
If there are no Militia cards in the battle, there is no effect. Destroyed Militia remain until the end of the battle.
Wraith[]
Official Glossary entry from 1.4 Rules
If there are no Militia cards in the battle, there is no effect. Destroyed Militia remain until the end of the battle.