If it doesn't clash too much with the theme of the class, I would consider giving the Cynosure a couple of spells other than their specialized spell, to give them a little flexibility. Maybe just 2-3 cantrips & 2-3 1st level or above spells, not gaining more spells at higher levels, but able to retrain them when they level similar to sorcerers/bards/warlocks. A player who wants to play along with the theme could even choose spells that seem like extensions of their singular spell; for instance if your singular spell is wall of force, you could take Ottoluke's Resilient Sphere and Forcecage when you reach the appropriate levels...I think the main reason to include such options is that if your singular spell is a utility spell, you don't want to feel useless in combat; maybe a picked a divination spell as my singular spell, so it would be nice to be able to still cast Firebolt in combat. I would consider making these side spells less efficient to use though, like giving them a higher spell charge cost. In the end, if you decide the class shouldn't have extra spells from the class, a character could still probably get by with spells from feats.
I really wanted to find a way to have a first level spell increase organically level by level, either by making specific improvements upon it or by jumping it to a related spell of the next higher level. But, the task of specifically improving a spell likely would be too much of a burden to place on a player and DM, and I could find no clear way to categorize existing spells as they increase in levels.
Yes, the feat spells (as well as racial spells or weapon proficiencies) were a compromise I had in mind that could add some utility.
A player who felt the need for this utility could play as:
- a high elf for Elf Weapon Training & a cantrip (or similarly a drow),
- a variant human to gain spell or weapon feats,
- a dragon born for breath weapon,
- tieifling with Infernal Legacy (or Barbed Hide),
- natural weapons of a lizard folk or tabaxi
- a hobgoblin's Martial Training
- Yuan-ti's Poison Spray and Suggestion
I do have a couple of questions though. What kind of builds did you anticipate players to make of the Protean?
Honestly, I haven't played other of these yet. I have been working on alternative classes, seeing what direction they could go so these have their genesis from thought experiments. What would a spell specialist look like? Then the Protean came from the opposite approach: what would a character with super utility look like? I thought about a Protean having signature features from various classes such as Sneak Attack, Rage, Action Surge, etc. But then I decided that feats were a much easier and less toe-stepping solution.
One thing I am working on for the Protean is a temporary or ad hoc Feat at level 2, maybe he gets to select a feat for 1 minute per short rest. It makes him much more versatile. I guess it would have to be magical otherwise why would he forget the feat. This would allow the feat selection to be situational.
Also, one option of Singular Power is "substitute spell concentration damage save DC to your Intelligence score or half the damage you take, whichever is higher." I'm afraid I don't understand what this means, could you explain it a different way?
This is what I meant to substitute your Intelligence score for the normal DC 10 for Taking Damage on holding concentration, but now I realize that's not balanced. Perhaps it should say: "add your Intelligence modifier to your Constitution saving throw to hold Concentration."
I appreciate your time.