Monsters are crawling again! Together with these brand new sets, shown at 15th May 2013 and released via Supply Drops in the Premium Store, the classic Halloween sets escaped the Vault and settled in the new Inland Invasion night. Each set is available in supply drops, normal ones costing 999 Funds and Bizzare and Fangtastic 1 499 Funds.
In the trailer, it is said, that drinking too much tonics causes the hero to mutate. This does not work in-game, however.
The National set has a background story but the royals doesn't. Yet.
The only hint about Royal monster is the part from Bizzare Creation introduction, wich says: They come from outer space, saw the Battlefield dvided into the two factions and decided to support Royalsagainst the Nationals as a part of their expansion plan. This implies that mutant's Bizzare set is not a mutated human, but an actual mutated alien.
The royal sets are based of a group of people who mutated into mutants then the bizzare set is a group of mutated aliens.
Unlike the royal sets the national's are based of one person who mutates in to the night watcher then further mutated into the nightwatcher's fangtastic set.
It seems that the monster designs where isnpired by cult/classic horror movies: the Royal's monster design is inspired by the Toxic Avenger, while the National Moster's design can be traced back to Nosferatu.