Geometry Class, But Make It Spells
Most people play area of effect spells like they work on vibes. You point, the spell happens, creatures nearby take damage. That’s mostly right, but the actual rules have some wrinkles that change what’s possible in ways that don’t get talked about nearly enough.
Line of Sight Is Not the Same as a Clear Path
This one trips people up constantly. To target a creature directly, you need an unobstructed physical path to them, not just the ability to see them. A pane of glass blocks a spell even if you can see the target through it perfectly. On the flip side, if a spell just says “a target within 30 feet” without specifying “a target you can see,” you don’t need line of sight at all. Blind, in darkness, doesn’t matter. The phrasing of each individual spell is doing real work there.
The Cube Rule Nobody Uses
For area of effect spells, you need a clear path to the point of origin, not to every creature inside the effect. This is what lets you drop a sphere around someone behind total cover. You can’t target them directly, but you can see the empty space next to them just fine.
The cube shape is where this gets genuinely interesting. The point of origin can sit on any point of any face of the cube, and the effect expands from there. You’re not required to center it on a face or project it straight out in front of you. Think of it like placing a block in Minecraft: if you can touch a corner, the whole thing goes down. There’s a lot of untapped shenanigans in that ruling.
Combining Spells Is the Real Endgame
The Player’s Handbook says almost nothing about combining magical effects, which is either a cop-out or an invitation depending on how you look at it. The only hard rule is that the same spell doesn’t stack with itself. Beyond that, it’s largely open territory.
Some combinations are straightforwardly brutal. Polymorph something down to under 100 HP, then use Power Word Kill. Power Word Kill doesn’t deal damage, it just kills, so the Polymorph rule about reverting at 0 HP is completely irrelevant. At level 9 that feels like overkill, but it’s clean.
Some combinations are just delightful. Detect Thoughts gives you surface-level thoughts by default, but pair it with Minor Illusion to plant something specific in a target’s mind and you can effectively steer what they’re thinking about. That’s not listed anywhere as an official interaction. It’s just creative use of two spells working together.
Then there’s Conjure Woodland Beings into Polymorph. Conjure eight pixies. Pixies can cast Polymorph. Congratulations, you now have eight Polymorphs. The encounter just became a chicken farm.
The attack roll side of things is less exotic. Spell attacks work almost identically to weapon attacks but use your spellcasting ability modifier instead of Strength or Dexterity. Casting a ranged spell attack while a creature is within 5 feet gives you disadvantage, same as ranged weapons. Melee spell attacks don’t have that problem.
One practical note: write your spell save DC in a visible spot on your character sheet. It’s 8 plus your spellcasting modifier plus your proficiency bonus, and you’ll use it constantly. The standard sheet buries it. Don’t let it stay buried.