In the rule “Sea Monsters” rewrite:

A Sea Monster’s Affiliation may be either Pirates or Ninjas. Only Pirates may summon Sea Monsters affiliated with Pirates. Only Ninjas may summon Sea Monsters affiliated with Ninjas.

So that it reads:

A Sea Monster’s Affiliation may be Pirates, Ninjas or Common. Only Pirates may summon Sea Monsters affiliated with Pirates. Only Ninjas may summon Sea Monsters affiliated with Ninjas. Sea Monsters with an affiliation of Common may be summoned by Captains of either Role.

Also rewrite:

As a weekly action, a Captain may summon a Sea Monster Affiliated to eir Role by making a post to that effect.

So that it reads:

As a weekly action, a Captain may summon a Sea Monster Affiliated to eir Role, or of Common Affiliation, by making a post to that effect.

Create a new Sea Monster named “Silent Ship Destroyer”, of Common Affiliation, with a summoning cost of 100 gold and 50 Fruit. It has the following effect:

Sink target’s Ship.

Create a new Sea Monster named “Giant Squid”, of Common Affiliation, with a summoning cost of 50 gold and 50 Fruit. It has the following effect:

Reduce target’s Gold by 100.