The Slayer is a fighter who excels at fighting with multiple weapons and try to confuse their enemy. Usually adventurers who deal with groups of enemies such as goblins or kobolds become Slayers, as their fighting style works best when fighting multiple enemies. They learn to mix fighting techniques to confuse their enemy, and work well when surrounded. Sometimes they can even make blows meant for them go to another enemy. 

Stronger Fighting Style

At 3rd level, you have learned the techniques of a Slayer, and gain skillful Multi-Weapon Fighting. If you do not have the Two-Weapon fighting style you adopt it in addition to your previous one, but if you already have it you can now add 1 to roles to hit and for damage if you have a Martial, and a Simple weapon in hand. Finally all weapons that require only one hand gain the Finesse propriety for you.

Surrounded Combat

At 7th level, the more enemies surrounding you, the stronger you become. While in combat if you are adjacent to 2 or more enemies you deal more damage for each enemy. 

2 Enemies- Add 1D4 to damage rolls

3 Enemies- Add 1D6 to damage rolls

4 Enemies- Add 1D8 to damage rolls

5+ Enemies- Add 1D10 to damage rolls

Bloodied Warrior

At 10th level, when you are reduced to less than one quarter of your hit point maximum (rounding down) you can start adding 5 to all of your damage rolls. Also, you regain 20 hit points when you deal a killing blow. This feature may be used an unlimited number of times, but you lose each of the abilities when you go above one quarter of your hit points.

Betrayal Strikes

At 15th level, when an attack misses you role any die, on a odd number nothing happens, but on an even number they hit a different enemy within that is adjacent to you.

Slayers Strike

At 18th level, once per long rest you can substitute up to two damage dice for a D20, after the attack regain hit points equal to the total damage you dealt with that attack.