Whether you’re talking about Jaroo Ashtaff, the Level 7 Druid, from AD&D, a Goblin Wizard 14 from 3rd Edition, or a 5th Edition Archmage, the trickiest bit of creating an NPC spellcaster is filling in their spell list.
For example, let’s take a closer look at the 5E Archmage’s spellcasting capability:
Cantrips (5, at will):
1st Level (4 slots):
2nd Level (3 slots):
3rd Level (3 slots):
4th Level (3 slots):
5th Level (3 slots):
6th Level (1 slot):
7th Level (1 slot):
8th Level (1 slot):
9th Level (1 slot):
Now, obviously, in this case we can actually use the default spells provided in the Archmage stat block. But wouldn’t it get a little boring — in a game teeming with hundreds or thousands of amazing spell options — for every Archmage to cast the exact same set of spells?
And so here we are, picking out twenty-five spells one by one.
It’s laborious.
And particularly daunting if you’re creating a spellcaster on the fly in the middle of a session: The PCs zigged in an unexpected direction or zagged by unexpectedly picking a fight. Quick! Pick a dozen (or two dozen!) spells in the time it takes the players to roll initiative!
THE BLANK TEMPLATE
If you take a second peek at the blank Archmage template above, you’ll see the technique I use when this situation comes up at the table.
(Which, of course, it inevitably does.)
Rather than listing the spellcaster’s spells, I just list their daily capacity.
Then I’ll grab a copy of the Player’s Handbook (or its local equivalent; similar techniques work in a wide variety of games) and flip it open to the appropriate spell list.
When it comes time for the NPC spellcaster to cast a spell, I’ll simply choose whatever spell feels appropriate and add it to the previously blank template. Over time, the template fills in.
The drawback to this technique is that it requires a bit more system mastery, since you’ve just multiplied their spell selection each round from a list with a handful spells on it to literally every spell in the book. But it’s not like you need to actually memorize every spell in the book: with just a little familiarity, you can rely on the spells you’re familiar with, grab anything else that looks particularly cool or appropriate as the need arises, and slowly expand your repertoire.
Plus your Player’s Handbook is already flipped open to the right page, so thumbing over to the description of a spell you’re not completely familiar with should be fairly easy.
CONSTRAINING CHOICE
Another effect of this technique, obviously, is that if you play it for maximum mechanical advantage your spellcasters are significantly more powerful than they were before! After all, “they” get to pick any spell they want at the very moment they need it! That’s not fair!
First, good sir or ma’am: ARE YOU A GAME MASTER OR AREN’T YOU?
Just… don’t do that. Ask yourself, “Does it make sense for them to have this spell?” And, if it doesn’t, don’t use it. If you don’t think you can answer that question truthfully, then flip a coin or roll a die when in doubt.
If you want a different form of constraint, consider defining a spell “theme” for the NPC caster: Maybe they’re a fire mage or a defense specialist or a summoner. Limit their spell selections to this theme: In addition to making the encounter more flavorful, it will place a reasonable limit on you unlimited spell selection and maybe even push you out of your comfort zone, encouraging you to experiment with new spells you haven’t gotten comfortable with yet.
Another constraint might be eliminating 25% or even 50% of their spell slots. For example, we might take our Archmage template and do this:
Cantrips (5, at will):
1st Level (4 slots): X
2nd Level (3 slots): X X
3rd Level (3 slots): X
4th Level (3 slots): X X
5th Level (3 slots): X
6th Level (1 slot):
7th Level (1 slot): X
8th Level (1 slot):
9th Level (1 slot): X
With each X representing a spell they’ve already used today or, alternatively, a spell they’ve prepared that isn’t relevant to the current encounter (depending on edition and spellcasting class). This limited capacity counteracts, to at least some extent, the greater flexibility of their spell selection. Plus, it probably just makes sense more often than not: The NPC was probably just going about their day, casting their spells the way they normally do. It’s actually pretty unrealistic when every NPC spellcaster shows up with their full daily allotment of casting ready to drop on a single encounter.
SAVE YOUR SPELL LISTS
Whether you’re prepping spell lists in your adventure notes or jotting them down desperately in the middle of the session, save the list. Give it a label like “Fire Mage” or “Death By Lightning.” Copy it into a repository or drop it into a file folder.
Over time you’ll build up a valuable trove of spell lists. Eventually, you won’t be left scrambling when the players zig-zag: You’ll be able to grab the most appropriate list, give it a couple of twists, and run with it.
“First, good sir or ma’am: ARE YOU A GAME MASTER OR AREN’T YOU?
Just… don’t do that.”
Kudos. Too many folks don’t take that responsibility.
And of course a template with some spells filled in as “this type of caster always has at least these ready”.
And a “mood” selection – caster when feeling safe, feeling wary, or They All Have it In For Me!
I also have a spread sheet with the spells from the PHB. It has just enough info for each spell, on one row, to let me run it without referring back to the book. School, duration, range, VSM, and brief description. Some few spells require more info so I have the book page number as well.
For spell casters where I know their select few preferred spells I copy/paste the rows to a separate spreadsheet for use in play with that caster.
Another technique for quickly designing such stat blocks is doing Vancian casting like Wizards started doing in Monsters of the Multiverse.
In this instance, enemy spellcaster will have a spell he can cast 2 times per day, a spell he can cast only once, etc. This is also really easier to run.