Amazon Lily was nearly destroyed by both a Seraphim and Blackbeard, causing the island to be deemed unsafe for the Kuja.
The Mihawk-like Seraphim’s slash literally changed the shape of the entire island though Blackbeard gets no damage from this attack because of his extremely high level Armament Haki. Blackbeard already has shown one of the best Armament Haki feats in the series. By hardening his arm, he defended against a sword slash, which could cut Amazon Lily’s large mountain in half.
Another huge feat: see how easily Blackbeard overpowered Boa Hancock’s Conqueror’s and Armament Haki.