You may take control of an enemy Common Unit within 4 spaces of your Summoner. You must immediately Summon a Mutation card by paying its Summon Cost and placing it on that Common Unit.Possessed Wall
Choose an enemy Wall and place this card on top of it. The chosen Wall cannot be used as a summoning point while this card is on top of it. At any time, a player may choose to discard any 2 cards from their hand and discard this card from off the Possessed Wall. If the Possessed Wall is destroyed, discard this card.Mutation Rules
The Filth Faction introduces a new kind of Unit card to Summoner Wars - The Mutation. When summoning a Mutation, it must be placed on top of a Common Filth Unit that you control. The Values and Special Abilities on the Mutation card override those present on its host Unit. If a Filth player summons a new Mutation onto a Unit that already has a Mutation, the previous Mutation Card is returned to the player’s hand, and the new Mutation takes immediate effect. When summoning a new Mutation onto a Unit that already has a Mutation, reduce the new Mutation's Summon Cost by a number equal to the Summon Cost of the Mutation it is replacing. You cannot reduce a Mutation's Summon Cost below 0. When placing a new Mutation on a Mutated Unit, move all Wound Markers over to the new Mutation. All Abilities and Events that effect Common Units also affect Mutated Units. When building a custom Summoner Wars deck, Mutations can be added in place of Common Units and/or Champion Units. You can never have more than 1 copies of a specific Mutation in a deck.
Rulings and Clarifications
Q: If a Mutation is Stunned by a Deceiver and I switch the Mutation with another one, is the new Mutation Stunned too?
A: No. It is considered a different Unit, and thus it wasn't adjacent to the Deceiver at the beginning of the turn.
Q: What happens if I try to switch a Mutation for another one, but there are enough wound markers on the first one to kill the second?
A: The second mutation would die instantly. It would give the 2 magic to the Filth player (the new Mutation and the common under it). The first Mutation would go back to the Filth's player hand normally.