Shinwonryu is a Shinsoo manipulation style which can only be mastered by "Those who have opened the door" (most likely the Irregulars).
This technique compresses Shinsoo around onto a single point and releases it as a huge explosion. According to the "God" of guardians, this technique is far above what ordinary Regulars can hope to achieve; a small amount of Shinsoo can cause great destruction. A tired Baam, using a single baang of this technique on a pack of big Crystal Shards, was able to utterly annihilate all of them in an instant lending credence to the sheer power of the technique.
It is likely the true name of this technique will remain hidden until SIU reveals the corresponding hanja.
SIU based the visual on "light" rather than "water" for shinsoo.
The technique has been shown to be able to surpass the spell endowing immortality to 43rd Floor inhabitants. This has been assumed by the fandom to be a result of the way the shinsoo is controlled.