I've played 5 games with Siren vs Paladin (as both mages). The Siren has lost every single game by a mile. She just seems very weak.
Sure, she can set up traps, but by the time she sets them up they only delay her troubles.
Her equipment is underwhelming. One of her rings is only useful for half of the rounds in the game while the other ring doesn't get a cost reduction from all water spells, only hydro and aquatic. Her ability to sustain psychic spells hasn't proven to be as helpful as I had hoped. She practically requires a Meditation Amulet since she seems to be constantly starved for mana.
I have been very disappointed with most of her creatures (save for Naiya, who is excellent). The sharks aren't strong enough. The pirates aren't strong enough. None of her level 1 or 2 creatures are worth casting because the most they can do is buy you time - The Siren appears to have a lot of ways to delay threats but few ways to actually deal with them, which is frustrating. The creatures she has that actually ARE effective are extremely expensive... which really makes me wonder why she only has channeling of 9. And then there is grapple, which honestly isn't that good. Even though its a condition marker it isn't hard to escape, and by the time my creatures do have something grappled they are half dead because I have few ways of keeping them alive.
As far as incantations go she has... well she really only has dissolve. And the only good water attack spell she has that you can cast regularly is surging wave.
What am I missing here? She comes off as a mage who is spread to thin with not enough focus on one thing.