Silent runic tongue

Sirens are known for their beautiful, mindcontroling voices. They are also know by the screeches they truly sing. What they are not known by and they should be is by their unic way of underwater communication.

Sirens are know for having unique patterns on their hands (both left and right identical in each person tho). They have developed a innate magical spell that allows them to telepathically communicate with each other if they know each other patterns or are seeing them. No other sophontic species have been able to communicate with sirens this way, demonstrating that both individuals must have and know each other patterns for it to work. It was a hard thing to demonstrate and is still not 100% believed because, as it is an innate spell from sirens, it is hard to teach to other people.

Once two (or more) sirens know/see each other patterns, they were able to speak in each other minds, conveying information with not words but yet able to convey the information without comprehension errors. This way of communicating doesn't seem to have a max range as far as each other know their patterns.

There is a limit tho, other than knowing the patterns, and it is that both sides must accept to communicate. WHen a siren is communicating without another to know, the second one will recieve a feeling that the other siren is communicating although they don't hear the message. It has become a tradition to start a communication with a sentence similar to "Hello, I'm ████. Are you free to talk?" and they wait for an answer. If after three attempts the other hasn't accepted, they stop.

This language, being magical in its core, has suffered consequences of traveling to Iphars. Sirens,w hile still able to communicate this way, they have a low possibility that their message wont arrive the other person, or will arrive to the *wrong* person, or will arrive being unable to comprehend, or would give both sides of the channel HEAVY headaches and confusion.