Still, it makes for an interesting solo option for the Siren: Buff herself up and give herself an additional Melee +2 every round, like a 1-mana Power Strike that doesn't cost an action. It would also seem to prevent her succumbing to a Reverse Attack, since she wouldn't be allowed to attack herself (?). Combine that with Regenerate 1 as long as she's in an aquatic zone, and she's a very solid solo mage.
I think you overlooked the fact, that the call can only target non-mage creatures, though 
Hypothetically it is still a good question.
If I understand the question correctly, you are asking if you reveal a Reverse Attack on a creature that is not allowed to attack itself, what happens. This is covered in the rules supplement.
When this creature is attacked, you must reveal Reverse Attack during the Avoid Attack Step. The attack is avoided and then redirected back; this creature becomes the new source (although the attacker stays the same), and the original source becomes the new target (even if the original source would not normally be a legal target), for the next 2 steps (Roll Dice and Damage and Effects). Then, destroy Reverse Attack. If the attack is Unavoidable, destroy Reverse Attack without effect.
Hypothetically it is still a good question.
But yes it goes on other non-mages
Emphasis is mine. Even if the attacker is not normally a legal target for the attack, Reverse Attack still functions. So the creature would still hit itself. Some other pertinent examples include:
1. [mwcard=MWSTX1CKJ02]Wizard's Tower[/mwcard] casting a [mwcard=MWSTX2FFA01]Devil's Trident[/mwcard] and getting it reversed back.
2. [mwcard=FWC16]Thoughtspore[/mwcard] casting a [mwcard=MWSTX1CKA01]Surging Wave[/mwcard] and getting it reversed back.
Both are examples of where the attacker would not normally be a legal target, but are still subjected to the attack when Reverse Attack is used.
