[RPG] use a spell with a casting time of “Bonus Action” as the action


I get that some spells are "especially swift" to cast and thus have a casting time of "Bonus Action". But is there any reason I couldn't cast such a spell as my Action?

Does it make a difference if the idea is for the one spell to be cast all by itself on a turn or if the desire is to use another Bonus Action (possibly a spell) on the same turn?

Best Answer

No. Actions cannot be traded for bonus actions.

Various class features, spells and other abilities let you take an additional action on your turn called a bonus action.

You can take only one bonus action on your turn, so you must choose which bonus action to use when you have more than one.

You choose when to take your bonus action during your turn, unless the bonus action's timing is specified, and anything that deprives you of your ability to take actions also prevents you from taking a bonus action. (PBR, p. 69; PHB, p. 189)

So by the rules you could use one bonus action from a spell without using an actual action but you could not use one bonus action as the actual action and another one as the bonus action.

You get 1 bonus action and 1 action. The action cannot be traded for a bonus action.

Rules as Intended agree

Lead rules designer for 5e, Jeremy Crawford agrees in this tweet:

Q: Can a bonus action be used as an action? Using two bonus actions in one turn: one being the bonus action and the action to do a bonus action.

Crawford: Actions and bonus actions aren't interchangeable.