Glad you put this here, Dag.
I've spent many hours from my limited online time in the last few days just to figure out at least one real nasty deck with my newly aquired So(a)Ps, but all these hours of nervewreckage finally brought me to the conclusion that it's just another theoretical powercard in Water's arsenal - alongside with Flooding.
The card's main targets would be (at least as I figured so far) Water's fragile little creatures: Squids, Physalias, Flayers, unupped Crawlers, or Puffers even, where the one turn damage loss doesn't matter that much, contrary to the big hitters where you're better off just playing another creature in almost any case (unless SoSa is in play; still, if chained, you're screwed anyways). Yet, even after they are soaped up, they don't put up much of a fight.
The +4/+4 with flooding sounds too good to pass, but even with the tightened flood-effect it's real hard to get there, it's a many card combo, and when you're finally there, you'll probably run dry of quanta by the time if you relied on squids/shield paired with the upkeep. Or if you operate with fractal, you find yourself lacking in defense, speed, and off-element quanta when completely countered by a single shield.
So the conclusion is: in almost any case it hinders you more than it threatens your opponent, and slows down a relatively slow element even more, which by itself is a suicide in the current fast-paced metagame. Sometimes I thought when playing that even the Permanent-freeze effect (which was the first idea of Zanz), though somewhat boring, would be much more of a service and overall useful than the current shard.
My best idea for a "slight" buff -while keeping the theme - would be making it a stasis effect also, delaying both sides of the field: this would eliminate it's suicidical (and almost unfair) disadvantage for you, but it may overshadow Sundial that way (though haste can still give you card advantage). Or just an additional Silence-like effect for your opponent in that turn. Personally I'd like to see the former, even the card text would be easy to modify.
Also it is real saddening to see how the AI fails to use it properly.