What Crinrict said.
I AM an occult player, and... yes.
Good mermaids don't have access to Summon Ocean Threat, Siren's Call, or Call Thunderstorm. Mean or Evil mermaids don't have access to Call Clear Skies, which is honestly my most used mermaid power and therefore makes Mean or Evil more of a deal-breaker for me than losing the powers that Good mermaids lose. (Mean or Evil mermaids also don't have Call Rain. Just thunderstorms.)
If your mermaids don't have the Good trait, this might be a bug, but do check their traits.
Summon Ocean Threat and Siren's Call need to be done in the ocean (not a pool). Er. Some of my mermaids are Good so I've barely used these, but yes, make sure they're in the ocean. The depth of the water makes a difference as well; Carl's Guide says Siren's Call is only available in shallow water. (I suspect that EA/Maxis doesn't want our mermaids killing anyone, and that would be more likely in deep water.) See if the depth of the water makes a difference on whether they can Summon Ocean Threat.
In short: Their traits make a big difference in what powers they get, which is why crinrict asked.
