Can you use a bonus action between the separate attacks of a spell?

Question

Similar to my recent question about moving between a spell's attacks I am curious about whether RAW you can use a bonus action between a spells attacks.

Unlike in the case of movement, bonus actions do not have a section specifying that they can occur in between parts of a particular type of action. The rules section on bonus actions reads (PHB, 189):

You choose when to take a bonus action during your turn, unless the bonus action’s timing is specified, [...]

The answer to this question is very relevant to Warlocks who might use Eldritch Blast against the target of their Hex but slay the target before every blast of Eldritch Blast has been used. The Warlock would then want to target a new creature with the remaining blasts (see this answer on changing targets during a spell) but first use their Bonus Action to move Hex to the new target.

If the particular bonus action is relevant to your answer, you can use the moving of Hex to a new target as the use-case - but I would also appreciate a general understanding of when, if ever, bonus actions can split up a spell's attack.

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Related: Can you use a bonus action from Cunning Action in the middle of an Attack action?

Answer 1

Yes, you can use a bonus action at any time (including in the middle of an action) unless specified otherwise

As you quoted in the question itself, the rules on bonus actions state (emphasis mine):

You choose when to take a 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.

In essence, you can take a bonus action at any time on your turn if its timing is not specified. Unless your ability to take the bonus action is dependent on a particular action being completed, nothing prevents it from happening in the middle of the multiple attacks of a spell.

The hex spell, for instance, states:

If the target drops to 0 hit points before this spell ends, you can use a bonus action on a subsequent turn of yours to curse a new creature.

Say you've cast hex on a target on a previous turn, and you're level 5, so your eldritch blast spell creates 2 beams. If you cast eldritch blast and your first beam reduces the target to 0 HP, you can use a bonus action to move your hex to another target before you make the attack for your second beam.

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Rules designer Jeremy Crawford reiterated this fact in an unofficial tweet from May 2018 (after some people were confused by an earlier tweet meant to indicate that bonus actions dependent on the Attack action could not occur between the multiple attacks of that action):

[...] A bonus action that has no trigger—such as Cunning Action and the misty step spell—can take place whenever you want on your turn (PH, 189).

The clarification repeats what the rules indicate: bonus actions whose timing is not contingent on a specified action can be taken at any time, including in the middle of an action.

Answer 2

You can take a bonus action at any time unless its timing is specified, in which case the bonus action has its own restrictions

You choose when to take a bonus action during your turn, unless the bonus action’s timing is specified [...]

This explicitly details that bonus actions can be taken whenever you want on your turn, and there is no reason this would not include times such as in-between actions that involve multiple attacks.

If a bonus action has a specified timing then you must first satisfy that individual bonus action's timing requirements.

The only timing I can think of that would prevent a bonus action from being used mid-eldritch-blast would be "when you take the Cast a Spell action", but as far as I'm aware, no bonus action has this trigger; many have the trigger "when you cast a spell" but this is satisfied before the spell's effects (such as hit/miss and damage) are even resolved.