What's a pirate game without a skeleton king? Maybe when he gets destroyed he breaks up into smaller skellywags as a skill. Like the golems in COC.. I think that would be a nice feature to add to the game.
Uhh... maybe a Brute Emperor? (similar to Barbarian King in CoC) Or Even... Heavy Gunner Chieftain! (Archer Queen)
We have something close to that with @Skull King http://forum.plunderpirates.com/index.php?threads/my-new-pirate-avatar.6112/#post-46463
I played dota 2. The hero once called skelaton king has the ability to reincarnate himself. Although with a LONG cooldown time. Maybe add that? Well since witch doctors can already do it, maybe he throws a fireball at a certain target dealing a whole lot of damage.
My ideas - skelaton king (up there) - lord of defense (juggernaut overlord) - black beard (giant buacaneer) - vodoo master (makes pirates go were you want not attacking a wall when the one next to it is already destroyed) - cannon master (guy that shoots with cannons) - High priestess (healing and alot of dmg)