You control at least five in any combination of Assassins, Pirates and/or Vehicles.
You are able to tap at least five Assassins, Pirates and/or Vehicles you control each turn.
Steps
Tap at least five Assassins, Pirates and/or Vehicles you control, either by declaring them as attackers if they don't have vigilance or by using any other method.
At the beginning of your end step, Edward Kenway's first ability triggers, creating at least five Treasure tokens.
Activate Time Sieve by tapping it and sacrificing five Treasures, causing you to take an extra turn after this one.