Marineford

But the death of fire fist Ace at Marineford changed everything because it was an unavoidable necessity in order to pave the way for the main character's development.

This can be seen in his role in executing Ace, as well as his fight with the Whitebeard pirates during the Marineford War.

After destroying half of Marineford, Shiki was finally imprisoned in Impel Down.

His actions on Marineford and his friendship with Luffy also prove a surprising capacity to see past classes see people as people.

The Golden Lion attacked Marineford after news of Roger's execution broke out and took on Sengoku, Garp, along with several other Marines all by himself.

He taught Luffy how to use Haki after the war of Marineford was over.