Treacherous

The Treacherous (裏切り者 Urigirimono "Backstabber" in the OCG) archetype is a group of DARK Warrior-Type Level 5 monsters revolving around attacking monsters that are on their side in order to gain added effects, as well as manipulating monsters into changing controllers for various abilities. They all share names that are similar to famous historical traitors and spies.

Play Style
All of the "Treacherous" monsters contain the following text: "This card can attack other monsters you control. [Insert Unique Effect Here] While this card is face-up on the field, if it destroyed a "Treacherous" monster(s) you control by battle, it gains the same original effects as the destroyed monster(s), also it gains this effect. ● [Insert Unique Effect Here]" Their powerful capability to attack each other leads to their primary strength: by sacrificing one's Life Points and by taking down their own allies, these craven Warriors are able to not only unlock some rather powerful effects of their own, most of them increasing their ATK, but also, if they took down a fellow "Treacherous" monster, they gain those effects as well. This lets them build up incredible effects to take on their opponent's monsters. Furthermore, some of their cards allow for you to Special Summon "Treacherous" monsters onto the opponent's side of the field or change control of a monster you control to gain more incredible bonuses. As such, cards that create Tokens would be useful for such play. Their primary weakness is their relatively slow speed, as their deck takes a bit of time for their momentum to build, though a clever player would use the weaker "Treacherous" monsters to keep pressure while a stronger "Treacherous" keeps building up power.