Scerafin, a species of quadrupedal darkeyed dragon that resemble sharks but live on land, are known for their telescoping necks (range of 3 yards), razor-sharp lance (read: snout horn) and tailfin, and unusually high defenses (due to a combination of dorsal plating, scales, extra external ribs, underbelly plating), as well as for their signature attack: Gastric Reversion.
Like sharks, Scerafins can invert their stomachs out through their mouths to expel their contents, and often do so when stressed. Unlike sharks, Scerafin seem to control what's expelled from their stomach. I don't mean that they select certain items to stay and others to go, however.
I mean that they regurgitate their victims and cause them to attack the offender when they are sufficiently stressed. They also do this with ingested water, by the way, expelling it and manipulating it to blast opponents, or even forming the water into tentacles solid enough to whack and grasp attackers.
The question is, how do they do it? How is it possible for Scerafin to expel and then manipulate water or even their victims?
The research mages are very, very confused here, but they do have some sort-of related information on enchanted creatures you might find helpful here and there, as well as some notes below. If you're wondering how our best mages have no more related resources, well, this is the best we've got.
We know adventurers from Alendyias may allow themselves to be consumed to chance Enchantment gain, and we know these weird dragon parasites exist, so one theory is that they developed this to take advantage of both, but A) the chance of such a specific and strange adaptation developing naturally is almost zero and B) other dragons have similar problems and lack any adaptation that's even remotely similar.
Due to the ethical and logistical issues of studying this phenomenon, we have no idea if the Scerafin's control can be broken, or if it fades with time or distance. We also don't know how long a victim can survive inside a Scerafin before they can no longer function as a minion, what happens to creatures digested by a Scerafin with this apparent connection, or how these minions are treated overall (ex: if they are re-eaten after the attackers leave).
We do know, however, quite a bit about how these Reverted victims behave. They're sort of like zombies-almost singlemindedly aggressive, ruled by instinct, higher thinking suppressed. They defend themselves against attackers, but they are relentless in their defense of the Scerafin, seemingly heedless of life or limb, attacking adventurers without hesitation regardless of lack of arms or protection, chasing down armed opponents or attackers-but seemingly not too far, either the Scerafin want them close for protection or they are not allowed to leave the range of the Scerafin's control.
Once regurgitated, they focus their attention on whoever prompted the Scerafin to regurgitate them, attacking them relentlessly until they fall, drop their weapon and cower, or someone else attacks one of them. In the first case, they simply switch their attention to whoever is currently threatening the Scerafin. In the last case, the individual will briefly turn and attack the offender before returning their focus to the previous target. And in the middle case, they simply stand there around their victim, only moving aside for the Scerafin or (oddly enough) the adventurer themselves, who may push them aside and flee successfully if he or she is quick enough.
Finally, sometimes one will find a Scerafin surrounded by a small horde of slime-coated victims. These victims move with the Scerafin, massing around it, shifting position to intercept incoming adventurers, and will become aggressive and even rush en masse at anyone armed who comes within sight. In essence, Scerafin victims are simple-minded, relentless, and incredibly focused, fighting tooth and nail to take down their targets, and seemingly incapable of higher functioning-much like zombies.
Specifications for Best Answer:
Magic is generally symbolic, but it has a logical basis. This magical ability is connected to the digestive's system's natural function, it is an expansion and/or enhancement of that function. The two are related, and the best answer will take that into account.
Magic may be real here, but so is natural selection and development. This ability had to come from somewhere, and part of its origin lies in natural law, so please take those into account.
Don't be afraid to check out some of my other questions about enchantments, or to take leaps of logic based off of what I've put here I appreciate creative answers, and if you make a wrong assumption, I do appreciate effort and I will see you're set straight so your answer becomes that much better. Finally, please let me know if the question needs improvement, I'm open to and appreciate feedback!