Van Augur, nicknamed “The Supersonic”, is the sniper of the Blackbeard Pirates, as well as one of the Ten Titanic Captains and captain of the Third Ship of the crew.
Van Augur is possibly one of the greatest master marksmen in the entire series. With his favorite rifle Senriku, Augur is able to fire bullets over tremendous distances with extraordinary accuracy. This is shown when Chopper suggested to Usopp that the seagulls flying around their ship were sniped from an extremely long distance, Nami immediately disclaims it since they could not see the island Augur was on, saying it was ‘impossible’ for any sniper to do. Augur was even able to tell after he shot the birds that one of them did not die immediately, showing his immensely sharp vision. Another example of his immense marksmanship skills (which is seen in the anime) is when he shot through the bullets of Impel Down’s staff, and then through the barrels of their guns, destroying them. It was because of this that he was also able to discern Akainu being on board of the incoming battleship from afar.
Augur ate the Wapu Wapu no Mi, a Paramecia-type Devil Fruit that allows him to teleport himself and others from place to place.
A lot of people are mentioning how Van Augur having the Wapu Wapu no Mi is perfect in a 1v1 match-up vs Usopp since it forces Usopp to improve his Observation Haki and try to compete with a target who’s always teleporting somewhere else, along with the potential ability to warp his own bullets so that he never misses.
But I haven’t seen people mention the other reason why the Wapu Wapu no Mi is perfect for someone Usopp has to defeat: Usopp cannot escape him. It denies Usopp the opportunity to run and hide. With the the Wapu Wapu no Mi, Van Augur will always be where he needs to be to target Usopp. There is no time for Usopp to hide, get his bearings and come up with a plan. He needs to face him head on and cement himself as the superior marksman in order to defeat him.