Mermaids is an event that is a great counter-strategy to crew-heavy ships.
Mermaids is an event that has to be played at the start of your turn. You plop it down on a ship and it can't be given an action for a number of turns equal to the number of crew aboard when Mermaids comes into play.
Strategies and game play:
The best strategy for Mermaids is to disable your opponent's ship with a lot of crew and, depending on your fleet, either run over there and blast it while it's defenseless or use the turns it's disabled to make a mad dash for the gold.
Combos with other miniatures:
Mermaids is an event and isn't really able to take part in "combos" as such.
Ways to counteract it:
The best way to avoid Mermaids is to not have a ship with more than 3 crew on it.
It renders one of your opponent's ships completely useless. Awesome.
None. Cheap and very effective.
Artwork and aesthetics:
The artwork on this card is a very non-traditional (and thankfully non-Disney) looking Mermaid. I like it a lot.
9 out of 10. I put Mermaids in pretty much every fleet I build. There are those out there that claim that Mermaids is "broken" but I disagree completely. Pirates is supposed to be a game about digging up gold but too many people were turning it into a pure combat game. The most effective combat fleets all had 5-masted ships that loaded up on crew to get extra actions. Mermaids allows an affordable, universal strategy to make those that live by the sword die by the sword.