Good catch on the SCAG; I always forget that it has that nice little section on Warlock Patrons. Man, I really wish I could play a Warlock in someone else's game.
There are many monsters in this book that would be great to add to the already-published adventure paths; the
Deep Scion is one of these, being a perfect minion of the Kraken Society. That is a secret society that has turned up twice now, in Princes of the Apocalypse and Storm King’s Thunder, but neither time was it really the ‘main attraction’ of the adventure, as it were.
The Deep Scion art in Volo’s is pretty good. Of all the ‘stand and pose menacingly’ pictures in the book, this is one of the most menacinglyist of them all! It helps that the guy is a freakish assembly of all that is nasty and grotesque about sea creatures, plus a rather fetching suit of leather armour. He hits the mark for me, which is to say that I feel like washing my hands after looking at it closely for this post.
In terms of background, these guys are a cross between Deep Ones from Lovecraft and Changlings. They are kidnapped - taken from shipwrecks or plucked from the shore - and taken underwater to be converted into a nasty fish monster. This is known to ‘evil aquatic creatures’, which is vague enough to cover a multitude of sins by the DM. The ritual not only makes them horrid physically, it allows them to shapechange back into a normal looking person, to swim and breathe underwater, and it gets some fairly strong combat abilities to boot.
The Scion is in an interesting place as a monster. It has enough character as an assassin from the deeps and shapeshifter, to suit a solo encounter - and its
Psychic Screech doesn’t distinguish between friend or foe, so it works a little better this way, mechanically. In addition, they have the skills (Deception, Stealth, etc) to work well as the infiltrator type. However, it is only CR 3. On the other hand, as minions of a greater power, they seem perfectly serviceable to be used in mobs against higher-level players, serving as the Ogres of your campaign if that makes sense. Note that a Kraken will only fail the saving throw against
Psychic Screech on a natural 1, so they’ll do perfectly fine as bodyguards for one. Both options are viable in the same campaign of course; note that the
Psychic Screech mentally transmits its knowledge of the last 24 hours to its master, so they seem perfectly suited to serve as the transition between the early stages of your story, with an investigation into strange happenings in the coastal village culminating in a fight against the Deep Scion, and the middle, where the players take to the water to find out who was
really behind events. This would then lead into fights against Sahuagin swarms or Merrow or whatever.
In combat, they are fairly uncomplicated. It turns into the squamous critter that it is in the picture, then either uses
Psychic Screech, which is an AoE save effect that causes stunning for a round, exactly like a Monk fist, or they can use a triple-attack routine for standard looking damage. The Screech is going to be way more scary when there are other monsters around to take advantage of anyone who fails. They are easy as pie to hit, but have very respectable HP, which I think is balanced out according to the monster tables in the DMG. There isn’t much otherwise to note, other than that they swim good.
A pretty simple monster for CR 3, especially as the monsters in this book are more complex overall than those in the MM, but there is a lot to like about these guys for a game set on the coast. I’ve got some thoughts about having them infiltrate Waterdeep’s Dock Ward, with the players asked to investigate the extent of the problem after the Merfolk in the harbour catch one trying to swim into the harbour.
Tomorrow we get the Demons. I’ll see how much space the Babau takes up; we might cover two or three at once, if there isn’t a huge amount to say about it.