Do saving throw based spells that do damage count as attacks? [duplicate]

Question

During our last session, two of my players got involved in a little PvP, and the Rogue was fireballed by the Wizard as a last act of defiance, hoping to take the Rogue with him as she died.

The rogue was high enough level to have the Uncanny Dodge class feature, and wanted to know if it applied. I was unsure, and looked over the rules, and didn't come to a final conclusion. I ruled that it did, in the moment, but it didn't actually matter that much, since the fireball didn't do enough damage to bring down the rogue, even with a failed DEX save and without Uncanny Dodge. But I would like a ruling I can stand by in the future, so the short version of my question is as follows:

Would a spell that does damage via a saving throw count as an attack, for the purposes of Uncanny Dodge? Or does an attack have to include an attack roll?

Answers must be supported by either a quote from the Player's Handbook, Dungeon Master's Guide, or a tweet from one of the developers of the game.

Answer 1

The definition of Uncanny Dodge covers this for you:

Uncanny Dodge Starting at 5th level, when an attacker that you can see hits you with an attack, you can use your reaction to halve the attack’s damage against you.

Fireball is not an attack anymore than spike growth is.

This is supported in the PHB pg. 195:

If there’s ever any question whether something you’re doing counts as an attack, the rule is simple: if you’re making an attack roll, you’re making an attack.

Since fireball requires no roll, it does not quantify as an attack.

Answer 2

From the Player's Basic Rules v3.4, page 73:

If there’s ever any question whether something you’re doing counts as an attack, the rule is simple: if you’re making an attack roll, you’re making an attack.

A fireball involves no attack roll, so it isn't an attack.

Answer 3

This is another example of specific beats general in the D&D 5e rules.

The General Rule

From pp. 193-194 of the PHB, the general rule for an attack is:

Making an Attack

Whether you’re striking with a melee weapon, firing a weapon at range, or making an attack roll as part of a spell, an attack has a simple structure.

Attack Rolls

When you make an attack, your attack roll determines whether the attack hits or misses. To make an attack roll, roll a d20 and add the appropriate modifiers. If the total of the roll plus modifiers equals or exceeds the target’s Armor Class (AC), the attack hits.

An attack is intrinsically and explicitly linked with an attack roll. If you roll to hit an AC then you are making an attack, if not then you are not making an attack; unless there is a specific rule that overrides this. It doesn't matter if your action causes harm (e.g. Cloud of Daggers, Magic Missile, Power Word - Kill etc.); if you don't make an attack roll it is not an attack unless there is a specific rule that says it is.

Consequently, the Uncanny Dodge feature does not help the rogue against the Fireball.

The Specific Exceptions

There are, to my knowledge, two cases that are specifically attacks even though they use Skill Checks rather than Attacks: Grapple and Shove both described on p. 195 of the PHB and both describing themselves as a special melee attack.

... you can use the Attack action to make a special melee attack, a grapple.

... you can make a special melee attack to shove a creature, ...

Edit - official WotC advice

I found this:

Does Uncanny Dodge work automatically against every attack a rogue or ranger gets hit by? Spell attacks too?

A use of Uncanny Dodge works against only one attack, since it expends your reaction, and only if you can see the attacker. It works against attacks of all sorts, including spell attacks, but it is no help against a spell or other effect, such as fireball, that delivers its damage through a saving throw rather than an attack roll.

... Which is clearly in line with the rest of my answer. Phew!