Spell Levels, Spell Slots, and Why Warlocks Don’t Count
Spell levels and character levels are not the same thing, and if you don’t get that distinction early, a lot of D&D’s magic system will feel like a mess. A 17th-level wizard casts 9th-level spells. A ranger, as a half-caster, tops out at 5th. The numbers run parallel, not together.
The spell level itself is a rough measure of power and complexity. First-level spells are your Magic Missiles and your Catapults. Third level gives you Fireball. Fifth level gets you Wall of Force and Mass Cure Wounds. By 9th level, you’re in Wish territory, which is less a spell and more a negotiation with the universe. There’s also a spell literally called Weird, which conjures mass nightmares and does 4d10 psychic damage, and which is somehow a 9th-level slot. No, it’s not worth it.
Spell Slots Are a Currency
Every spell from level 1 through 9 costs a spell slot of at least that level to cast. You have a limited number at each tier, and when they’re gone, they’re gone until a long rest. The key thing people miss: spending a slot does not remove the spell from your list. You can cast Magic Missile with all three of your 1st-level slots if you want. Nobody is stopping you.
Running out of low-level slots doesn’t lock you out either. You can cast a 1st-level spell using a 2nd-level slot. Magic Missile cast at 9th level fires 11 darts. Has anyone done this? Probably. Should they have? Debatable. The spell scales, but not in a way that competes with actual 9th-level spells, so you’re overpaying in a way that only makes sense when you’re completely out of options.
Known vs. Prepared
How you access spells depends entirely on your class. Wizards write spells into a spellbook, and that book is their known list. Clerics know the entire cleric spell list but prepare a subset each day after a long rest. Sorcerers know a fixed number of spells and can’t swap them out freely, but they never have to prepare anything. Bards are similar, just with more flexibility on swapping.
Cantrips sit outside all of this. They’re 0-level spells, they cost nothing to cast, and you use them constantly. Prestidigitation, Minor Illusion, Mage Hand (yes, it’s a cantrip, not a 1st-level spell), these are the spells that define your character’s moment-to-moment flavor. Most casters cap out around four cantrips, and there’s a reason for that. The good ones are genuinely powerful when there’s no resource attached.
Ritual casting gets its own carve-out. Spells tagged as rituals can be cast without a slot if you spend an extra 10 minutes on the casting. It’s a flat 10 minutes regardless of the spell’s normal cast time, which is a strange design choice, but functionally it means: don’t bother in combat, use it freely when you have the time. Not every class can ritual cast by default. Clerics, druids, and wizards get it as a class feature. Everyone else needs the Ritual Caster feat.
One more thing before getting into armor: if you’re not proficient in armor and you put it on anyway, you cannot cast spells. Full stop. This is why the wizard is squishy. Mage Armor exists.