Each of your Pirates gets the Separatist subtype and can't lose its subtype.
Discard one of your Separatist Pirates from any arena Evade 4
Keywords
Evade
Evade X: A layered ability activated during the damage prevention POP that means, "Prevent up to X damage to this unit." You can play Evade only once for each instance of damage. You don't have to use all of the Evade. You choose how much damage to Evade up to X, even if the full amount of damage or more is pending.