What is the value of an Action/Bonus Action/Reaction?

[Crucius]

So I'm making a very rare magic item that uses the action of one PC, and the reaction of two others. This means it takes 3 'actions' out of the action economy. Should a magic item be balanced around that? (same goes for an item that has to be primed using a bonus action, then activated using an action for example)

Some quick maths: Let's say you want to make a strong item (otherwise it probably wont get used, you know how it is), so you take fireball damage (action) + 2 opportunity attacks (2 reactions) worth of damage; 8d6 + 2*(3d6) (~1d10+4 damage on average) = 14d6.

Now that is... quite chunky. It's the power of a fireball at 9th level. Is it fair to take the two reactions into account when determining the damage for the item?
Or maybe the broader question is: should an item's damage be determined by the amount of 'actions' spend on it, or should there be a ceiling of damage that can be delivered in one burst?

If an item's damage IS determined by the amount of actions, then what is the value of an action, bonus action and reaction? (quantity being damage, and unit being d6 I guess?)

(I know actions can be used on various non-damaging things which can be much more valuable, and most of it will be determined by classes, but I mean on average based on damage potential of things that do do damage hehehe, do-do)


Rings of the Triumvirate (Very Rare, Requires Attunement)
A trio of rings carved from solid grey matter.

The Weave reverberates between three psionic nodes, unleashing a torrent of psychic energy. As an action you can spend 1 psi point to choose two allies within 30 feet of you that also wear a ring, and who are also 30 feet within each other. They can use their reactions to also spend 1 psi point. Each creature within the area between you and your allies must make a DC 13 Int saving throw. On a failed save, a target 6d6 psychic damage from each creature that spent a psi point, or half as much on a successful one. The saving throw is made with disadvantage if both allies spent a psi point.

Once a psi point is spent on the ring, it can’t be used again until the next dawn.

(with psi points being a campaign specific thing, which in and of itself are quite scarce, but have so far no other in-combat uses, so you can disregard them basically)
14d6 would translate to 5d6 per person, but I wanted to future-proof this bad boy so I added another 1d6 (the party is now level 9 and they are seriously punching above their weight)

[KorvinStarmast]

Clunky albeit interesting. (Reminds me of the power of spell casting circles in the Darkover novels). Reactions happen on someone else's turn, so the lost value is that no other readied action can be taken, no OA can be made, and any ability that calls for reaction (shield spell, certain class features, one of the feat Sentinel's features) are voided.

[Democratus]

Hard to balance, since the value of an action, bonus action, or reaction depend heavily on the character spending it.

[Man_Over_Game]

Hard to say.

The basic value of an Action is an Attack, which is roughly worth 10 damage, before accuracy comes into account. However, the number of attacks and damage you deal per-attack scales with your level, at a rate I'd estimate as increasing every 5 levels.

So a level 1 Action is worth 10 damage, level 5 is worth 20, level 10 is worth 30, level 15 is worth 40, and so on. Not quite 100% accurate, but it's accurate enough after taking account of special powers, spells, Action Surges, and so on.

Reactions aren't much different than circumstantial Attacks, although they don't scale quite as well. We could probably estimate them as being worth 1/3 or 1/4 of an Action, considering how rarely they utilize something like an Opportunity Attack in 5e. They do still scale, after taking into account stat buffs, feats, spells, magic items, and so on, but obviously not quite as much.

Bonus Actions are probably worth about 1/2 of an Action. They are generally circumstantial, and don't often provide a benefit without some kind of extra cost (like with Misty Step). Sure, a Rogue can Disengage and Dash with just his level 2 feature (which is, itself, a cost), but it's not like EVERY possible Action is made available at the same time. There aren't any examples of someone getting something like the Attack Action or Cast a Spell Action for free, so we can assume that the Disengage and Dash Actions are intentionally less powerful than the Attack/CaS Actions, and are correctly labeled as a level 2 feature. Even when taking into account the TWF scaling, in how your weapons downgrade for the extra attack, and the cost of the Fighting Style (when applied), it kinda matches up.

So, to put it roughly, I'd probably label it as:

Action = 1
Bonus Action = 1/2
Reaction = 1/4

Just make sure to scale stuff back up based on circumstance. The reason Opportunity Attacks deal as much damage as a normal attack is because they're rare and easily mitigated, but become more common as you level due to the larger number of enemies and Opportunity Attack features (like PAM)

[Crucius]

So, to put it roughly, I'd probably label it as:

Action = 1
Bonus Action = 1/2
Reaction = 1/4

Just make sure to scale stuff back up based on circumstance. The reason Opportunity Attacks deal as much damage as a normal attack is because they're rare and easily mitigated, but become more common as you level due to the larger number of enemies and Opportunity Attack features (like PAM)

My gut feeling agrees with these estimates. I find it also hard (especially for the reaction) to decide if I should take into account the rarity of a certain action to determine 'damage potential' (or 'expected damage'?). So the difference between "when it occurs, what's the value" and "value times occurrence".

As per usual I'm waaaayyy overthinking this whole thing, but eh, what can you do.