Well, I don't think I need to tell you that it's within RAW, per the spell description of Fireball [emphasis mine]:
A bright streak flashes from your pointing finger to a point you choose within range then blossoms with a low roar into an explosion of flame. Each creature in a 20-foot radius must make a Dexterity saving throw. A target takes 8d6 fire ...
Boy, so many people lining up to tell you "don't do it that way it's badwrongfun!" I'll offer a differing perspective, which is yes, absolutely, use a house rule to this effect. It has the desired effect of adding verisimilitude without "nerfing" or "ruining" anything. I shall offer up real play experience and not pure opinion ...
You're using the spell incorrectly. Note that the condition that causes the spell to damage a creature is when the creature enters the beam. It takes movement on the part of the creature (including forced movement) to do that. It does not cause damage when the beam just passes over a creature. As you note, that would be super powerful for a 2nd level ...
Overall, this will make area/multi-target spells less reliable, but more potent.
The chance of a single individual to save is not affected by this change. The number of individuals affected over multiple castings is also not (or just slightly) changed.
What changes is the number of individuals in a given group that make the save. Let's assume a ...
A GM shouldn't roll all-or-none saves. If reduced rolling is necessary, instead they should figure the expected number of saves, then add a d4 and subtract a d4. Below are pictured the results of this method for various numbers of enemies and probabilities of saving.
Read on to see how these are derived.
All-or-none is a bad idea. But the GM need ...
This meta-game accuracy is a purposeful feature of using the optional grid rules — that kind of tactical detail is the whole point of using a grid.
An obvious alternative that eliminates miniatures-based player precision is to not use the optional grid rules. There's some discussion of imprecise AoE handling on DMG page 249 (in short “make a call, consult ...
In a tweet from Jeremy Crawford, he says:
When a spell's description uses "enter" in relation to an AoE, the entering has to be voluntary only if the text says so.
By itself, it seems to imply that moving the Moonbeam counts as "entering".
But, in a Sage Advice article, he clarifies this:
Our design intent for such spells is this: a ...
It means 5 foot radius.
You pick a point (If you're using a grid, that would be a grid intersection)
All creatures within 5 feet (ie, squares surrounding the grid intersection) are affected.
If it only affected a 5-foot square, that would be a 5-foot diameter (or 2.5 foot radius).
This would be a great change if you were in a fight where you were almost certainly going to lose.
Imagine a spell that defeats 1/2 of the creatures it targets. You use it on 2000 creatures. If more than 10 survive after the spell is cast, you lose.
With one roll, you have a 50% chance of winning the fight.
With one roll per creature, you certainly lose ...
Magic is unaffected by creature size. Creatures can have benefits for particular types of magic (it’s easy to imagine a dragon getting bonuses on fireball—after all, their descendants do—or a pixie getting some benefit with illusions), but nothing automatic just for being larger. Any such benefit would be listed directly in the creature entry.
The Sorcerer is indeed Silenced by their own spell.
Nothing in the spell description excludes the Sorcerer from the spell. The only way to get around this is if the Sorcerer also has the Subtle Spell meta-magic skill selected so that they can remove the Verbal component.
Nothing about casting a spell makes you immune to it's effects unless it's stated in ...
A fireball or a similar AoE spell would not crit
The Unconscious condition does state that (from the SRD p. 359, emphasis mine):
Any attack that hits the creature is a critical hit if the attacker is within 5 feet of the creature.
An "attack" is a well-defined term in the 5e rules that is different from the basic English meaning of what an attack is. ...
Unlike some previous editions in which the fireball will adjust based on the space available and spread down corridors if contained, 5th ed simply states that the fireball will take up the amount of space listed as 20' radius sphere and spread around corners to fill that space, never expanding to exceed that distance from the point of origin. This ...
You do not need line of sight at all
Spells will tell you the requirements to cast them. All spells require (unless indicated otherwise), a clear path to the target, but line of sight is not a general requirement. In other words, spells only require line of sight if they specifically say so.
Here are the targeting requirements for wall of fire:
You create a ...
Shatter's area of effect is a 10-foot radius sphere. The description of a sphere's area of effect (PHB p. 205) explicitly states:
A sphere's point of origin is included in the sphere's area of effect.
Similarly a cylinder's point of origin is included in the cylinder's area of effect.
a cone's [or a cube's, or a line's] point of ...
They would be equally powerful, as magic effects aren't affected by caster size, only by spell level. The description of fireball says:
Each creature in a 20-foot-radius sphere centered on that point must make a Dexterity saving throw. A target takes 8d6 fire damage on a failed save, or half as much damage on a successful one.
[. . .]
At Higher Levels. When ...
This is very bad for you, and your whole party
This is not so much the question of mathematics, as what makes a game interesting.
3 Fire Giants charge your level 11 party, your spell DC is 17, their Cha save is 5. If you cast Banishment at 6th level, targeting all of them, the best case scenario is that 1 or 2 of them is ...
Yes, a caster is affected by their own AOE unless the spell or ability states otherwise
When a creature enters the spell’s area for the first time on a turn or starts its turn there, that creature must make a Constitution saving throw.
The caster is "a creature" certainly, so, barring anything in the spell that says otherwise, ...
Generally, all in the area of effect are effected by the spell.
Areas of Effect are defined on pp.204-205 of the PHB. Nothing in those general descriptions distinguishes between who might be in those areas.
Specifically, let's look at Burning Hands and Sleep:
Burning Hands: "Each creature in a 15-foot cone.... (PHB p.220)" Since your allies are (...
The description of Fireball on D&D Beyond clearly says to choose a point within range. It makes no requirement for hitting a hard surface - it makes no requirement at all, other than picking a point.
The spellcasting section says:
To target something, you must have a clear path to it, so it can't be behind total cover. If you place an area of ...
Because we are exploring line of effect, it is important to note what, exactly, the effect is. If the effect of light, for example, is to create light centered on the object, the transparent container blocks that light since it blocks line of effect via full cover. If, on the other hand, it makes the object glow brightly enough to emit that light, the ...
Yes, though a DM might not want to deal with abnormal spell positioning
In the Sage Advice compendium, a similar question was asked about the spell Cloud of Daggers:
Using 5-foot squares, does cloud of daggers affect a single square? Cloud of daggers (5 ft. cube) can affect more than one square on a grid, unless the DM says effects snap to the grid. There ...
RAW Fireball appears to ignore full cover, if there is a path fully within range of the effect that can reach the target, as this spell specifically travels around corners.
If there are no corners this spell can successively travel around within it's effect radius to reach the target, then the target cannot be reached by the effect, and has total cover, ...
It originates from a corner
Choose an intersection of squares or hexes as the point of origin of an area of effect, then follow its rules as normal. If an area of effect is circular and covers at least half a square, it affects that square.
As with most area spells, you don't target an enemy with it, just a patch of ground. So it covers 2x2 ...
The fortress is probably not designed to kill its user
You are correct that the text is ambiguous, in that it doesn't specify how or in what direction it expands from a 1-inch cube into a fortress 20 feet on a side. However, since it is a magic item that was designed by an intelligent mage who presumably intended to actually use their creation, it is ...
Here are some examples of the areas affected by a 15-foot cone cast at different angles.
The point of origin is shown at an intersection between squares (as recommended in the DMG), and also centered on the side of the square for attacks in a cardinal direction (which is more intuitive).
Here are all the squares that are touched by the cone:
Here are all ...
In the earliest rules, Chainmail with its Fantasy Supplement (Gygax & Perren, 1971), the fireball referenced the catapult rules for its mechanic. That includes the following optional rule (2E, p. 10):
Fire Optional: Roll two different colored dice. One color is for an over-shoot and the other is for an under-shoot. To
decide which number ...
Cloud of daggers fills one 5-foot square.
Neither of the options that you show are correct. The spell description states that it takes up:
a cube 5 feet on each side
Since one square is five feet by five feet, you can fill one square with the cloud. If you target the center of a grid cell, then the spell fills that entire grid cell.
Note that the spell ...