At the end of the day I feel like if I threw an enemy wizard at my party, and they shot off some cool spell, and my wizard player said
"Hey, that's really cool. I'd love to learn how to do that"
Me telling them 'Tough crackers, maybe you should have made a monster instead of a player character, neener neener boo boo' feels like letting them down. It doesn't have to be something they can do next round, or even next level.. But if they(Their character) is serious about it, they should have a path towards learning it.
Sure, and like anything else where a player has their character have a goal, this is an adventure hook. They don't know how it happens, but maybe they can get a clue with an arcana check.
If they want to go down that route as a party, you can do it. There is nothing super unbalancing about getting an ability like that after some in-game effort and possibly character resources being expended.
I'm not sure why you'd say "neener neener boo boo"?
I mean, if I see a ranged cantrip do 1d10+some mod of force damage, my first thought is going to be "Eldritch Blast + Agonizing Blast" unless I'm explicitly told otherwise. Cantrips don't get pluses to damage in most cases.
(And to be clear, we typically roll in the open in my games, so the damage calculation used would be obvious.)
So, they are using mechanical meta-knowledge in order to complain about a monster's abilities. That sounds like a them problem.
If they have an in-character reason to investigate what is going on, you ask for a knowledge check, etc. "What kind of spell was that" is a reasonable one to ask. Again, at this point your players are invested in this problem, which is an adventure hook and means as a DM you are justified in (a) using it to motivate adventuring, and (b) have the time budget to spend resources on mechanics or whatever.
This is no different than a custom magic item, a custom feat, a boon, or anything else you'd 'brew up as part of mechanical-story interaction?
I think the Hit Die is a typo, and should say 3d6 instead of 3d8. In any case, the Hit Points are correct.
No, not a typo: Monsters use the creature size for their hit dice.
Tiny: d4
Small: d6
Medium: d8
Large: d10
Huge and bigger: d12
Monsters (and NPCs by default) don't have character levels, so don't get character HD or HP.
Ability Scores are: 14, 11, 10, 10, 10, 10
I suspect the 14 is somehow "costing" higher scores elsewhere.
I think I like as a default array for a "typical" level zero: 13, 12, 12, 11, 11, 10
In any case, player characters can be above average.
In this case, this is an average humanoid (all 10s) with somewhat above-average intelligence.
Statblocks dont need to conform to player characters, but things like spells and cantrips do, especially if something bog standard the players are themselves, such as an Apprentice Wizard, which every lowest tier Wizard is.
That said, the statblock in fact is a simplified version of a level 2 Wizard.
No, NPCs spells and cantrips don't have to correspond to PC spells. And every single previous attempt in D&D to enforce they do so have
always made spellcaster monsters a super pain to work with.
We have a OD&D, BECMI, AD&D 1st, AD&D 2nd, D&D 3e, D&D 3.5e, Pathfinder and early 5e examples of this being a pain. Every single time it sucks horribly to run a monster which uses PC spellcasting. It is tolerable if it is a rare "BBEG" foe, but even there it is annoying.
It is known.
There are some people who don't mind the annoyance, but the vast majority keep on running into this and we don't like it.
PCs in general are more complex than monsters, because you have the full attention of a player tweaking its bells and whistles. Spellcasters are more complex than non-spellcasters by custom in D&D, and wizards doubly so. All of this is a very good reason for the ability to make wizard-archetype foes that don't require the DM to handle the full complexity of the most complex PC class as just one of the many things they are doing at once.
Hence emulation.
I don't personally love how the emulation is done here, they could do it better, but emulation itself is a no-brainer.