Yami Yami no mi

The Yami Yami No Mi is a Logia fruit that allows its user to produce and control darkness at their will making them a darkness human.

Pros

 * VERY BIG AoE which makes it good for PvE and PvP.

Cons
Lack of range and accuracy to trap your opponent, therefore you can't stun and pull them in front of you to do high damage combos. Only good at PVP if you have good accuracy.

Kurouzu only pulls in your target towards you stunning them for 1 second, But if you use it in conjunction with black hole you can make black hole be able to do damage with out the enemy getting out

Trivia
Blackbeard possesses both the Gura Gura No Mi and the Yami Yami No Mi, which he stole the Gura Gura No Mi from Whitebeard, and ended the legendary pirate's life.
 * The Yami Yami No Mi is used by Marshall D. Teach, also known as Blackbeard from One Piece.