Confusion Poison Assassin

Kill the Slow. The assassin has advantage on attack rolls against any creature, that comes after them in the initiative order.

Accuracy. Whenever you have advantage on an attack roll, you can reroll one of the dice once.

Mobile. When you make a melee attack against a creature, you don't provoke opportunity attacks from that creature for the rest of the turn, whether you hit or not.

Shortsword. Melee Weapon Attack: +5 to hit, reach 5 ft., 1 target. Hit: 13 (3d6 + 3) piercing damage. On a hit the target gets must make a DC 14 Constitution saving throw against the Confusion Poison.

On a failed save the target gets affected and can’t take reactions and must roll a d10 at the start of each of its turns to determine its behavior for that turn.

d10     Behavior
1     The creature uses all its movement to move in a random direction. To determine the direction, roll a d8 and assign a direction to each die face. The creature doesn’t take an action this turn.
2-6     The creature doesn’t move or take actions this turn.
7-8     The creature uses its action to make a melee attack against a randomly determined creature within its reach. If there is no creature within its reach, the creature does nothing this turn.
9-10     The creature can act and move normally.

At the end of each of its turns, an affected target can make a DC 14 Wisdom saving throw. If it succeeds, this effect ends for that target.

Cunning Action. The assassin takes the Dash, Disengage or Hide action.

Opportunity Attack. Look it up, it's amazing