To get the Death Step fighting style in Blox Fruits, start by acquiring the Dark Step. You can find the Dark Step Teacher at Pirate Village in the Second Sea or Castle on the Sea in the Third Sea. You need to pay $150,000 to learn Dark Step.
Next, master the Dark Step by reaching a mastery level of at least 400. You can achieve this by defeating bosses and large groups of enemies.
Gather the necessary resources: 2,500,000 Beli and 5,000 Fragments. You can obtain these by defeating bosses like Darkbeard and the Cake Prince, or by doing raids like the Flame Raid.
To get the Library Key, defeat the Awakened Ice Admiral boss at the Ice Castle. The drop chance for the Library Key ranges from 5% to 25%.
Finally, use the Library Key to unlock the door to the Death Step teacher. Pay 2,500,000 Beli and 5,000 Fragments to learn the Death Step fighting style. Follow these steps, and you’ll acquire the powerful Death Step in Blox Fruits.