Cantrip actions question.

Currently in a group that insists as of 5e becoming 5.5 that cantrips are now bonus actions by default. I have found nothing to prove this. The person who the group considers the "expert" of the edition insists this is the case in either the Player's Handbook or DM's guide. I would like to have a definitive answer on this because this feels like it has serious balance repurcussions and I would like to be able to keep a reasonable idea of encounter design vs intended action economy when its my turn to run the game for the group beyond just saying "my game, my rules."

They're objectively wrong. Every spell description, including cantrips, lists the casting time. For instance, if we look at Fire Bolt, we see it explicitly lists a casting time of 1 Action, whereas Shillelagh instead lists 1 Bonus Action. This is straight up from the PHB, if someone is insisting the descriptions aren't conclusive proof, they aren't arguing in good faith.

If the book doesn’t say so, do not trust people who say otherwise. Always double check your sources and check if it’s consistent with what they say, stuff like claiming all cantrips are bonus actions can easily be refuted due to the fact that they specify what action they use.

Quote from DarbotheShedDweller >>

Currently in a group that insists as of 5e becoming 5.5 that cantrips are now bonus actions by default. I have found nothing to prove this. The person who the group considers the "expert" of the edition insists this is the case in either the Player's Handbook or DM's guide.

This sounds like your "expert" can't point to any rule to actually back up that claim. That's because they don't exist and the claim is false. I don't want to assume dishonesty, but it would require a significant misunderstanding to come to that conclusion on their own. Perhaps they misunderstood an online video or article about a change or missed the context of a statement. Whatever the cause, they are wrong.

The definitive answer is that nothing has fundamentally changed about casting Cantrips (in general) between 5 and 5.5. Cantrips take the action listed in the Casting Time of their spell description. True Strike requires a Magic Action, for example. The spell says the casting time is 1 Action and the action for casting spells is the Magic Action. Most 5e spells, including Cantrips, can be used without modification from their original source. Some may require tweaks as related mechanics have changed.

What has changed is the restriction on casting spells with a spell slot during a turn. Now, you can only cast a spell with a spell slot once per turn, but as many spells without a spell slot of any level as you have actions/bonus actions for, assuming you have the ability to cast spells without a spell slot (Cantrips, Magic Items, Species Traits, and Feats are common ways to cast without a spell slot during your turn).

Of course, specific Cantrips may changed. True Strike (2014) is very different than True Strike (2024).

Some relevant rules:

Bonus Actions

Various class features, spells, and other abilities let you take an additional action on your turn called a Bonus Action. The Cunning Action feature, for example, allows a Rogue to take a Bonus Action. You can take a Bonus Action only when a special ability, a spell, or another feature of the game states that you can do something as a Bonus Action. You otherwise don’t have a Bonus Action to take.

You can take only one Bonus Action on your turn, so you must choose which Bonus Action to use if you have more than one available.

You choose when to take a Bonus Action during your turn unless the Bonus Action’s timing is specified. Anything that deprives you of your ability to take actions also prevents you from taking a Bonus Action.

The underlined section is important. Something must explicitly give you a Bonus Action for you to have one to take. There are no Bonus Actions available by default.

Casting Spells > Casting Time

Most spells require the Magic action to cast, but some spells require a Bonus Action, a Reaction, or 1 minute or more. A spell’s Casting Time entry specifies which of those is required.

One Spell with a Spell Slot per Turn

On a turn, you can expend only one spell slot to cast a spell. This rule means you can’t, for example, cast a spell with a spell slot using the Magic action and another one using a Bonus Action on the same turn.

Reaction and Bonus Action Triggers

A spell that has a casting time of a Reaction is cast in response to a trigger that is defined in the spell’s Casting Time entry. Some spells that have a casting time of a Bonus Action are also cast in response to a trigger defined in the spell.

Longer Casting Times

Certain spells—including a spell cast as a Ritual—require more time to cast: minutes or even hours. While you cast a spell with a casting time of 1 minute or more, you must take the Magic action on each of your turns, and you must maintain Concentration (see the Rules Glossary) while you do so. If your Concentration is broken, the spell fails, but you don’t expend a spell slot. To cast the spell again, you must start over.

The default assumption for all spells is that they take a Magic Action to cast. Any spell that takes 1 Action or longer requires the Magic Action. Every spell will have the cast time specified and must explicitly state that it requires a Bonus Action (or Reaction) to be cast with anything other than a Magic Action. Some features can change the casting times of spells. When this happens, again, it will be explicit. For example, a Warlock's Pact of the Chain allows Find Familiar to be cast a Magic Action instead of 1 hour if they have selected that invocation. Sorcerers can use the Quickened Spell Metamagic to cast a one action spell as a Bonus Action but must expend Sorcery Points to do so for each spell cast.

5E always indicate the casting time of a spell and 5.5E is no dfferent.

If you're looking for an official ruling that would reiterate it, you can show "expert" this Sage Advice'

Is there a limit on the number of spells you can cast on your turn?

There’s no rule that states you can cast only X number of spells on your turn, but there are some practical limitations. The main limiting factor is your action. Many spells require an action to cast, and unless a feature says otherwise, you only have one action on your turn. You also must abide by the rule of only expending one spell slot to cast a spell on your turn.

So, for example, if you take your Bonus Action to cast Healing Word using a spell slot, you can also take the Magic action to cast Vicious Mockery—a cantrip which doesn’t require a spell slot.

@DarbotheShedDweller maybe it's a (bad) joke from your DM? Isn't it April Fools' Day today? :)

I wonder if this person has gotten really confused about the change that was made to the rule about how many spells you can cast in a turn.

RE: Smite's underlined part on BAs... I'm not sure why I never clocked that before. I had always read it as, "You have an Action, a Bonus Action, and Movement on your turn. But you can only use your Bonus Action if you have something that costs a Bonus Action, otherwise it's wasted."

I guess it's the same thing for all practical purposes, though. I just found it interesting that you literally don't have a BA if you don't have anything that takes a BA.

Quote from sabin76 >>

RE: Smite's underlined part on BAs... I'm not sure why I never clocked that before. I had always read it as, "You have an Action, a Bonus Action, and Movement on your turn. But you can only use your Bonus Action if you have something that costs a Bonus Action, otherwise it's wasted."

I guess it's the same thing for all practical purposes, though. I just found it interesting that you literally don't have a BA if you don't have anything that takes a BA.

I think back when this stuff was originally written, they were expecting a lot of people to be coming from 4th Edition, where minor actions where more common and you were less likely to not have one you could do at any given time (especially since in 4e a lot of ongoing effects required you to use a minor action every turn to sustain them). So they may have wanted to explicitly say that it's normal to sometimes not have a bonus action you can do on a turn.