What does Halo of Spores react to?

Question

In the new Unearthed Arcana there is a new Druid Circle, Circle of Spores, with the following ability:

Halo of Spores

Starting at 2nd level, you can launch toxic spores at other creatures. To do so, you use your reaction on your turn to deal 3 poison damage to one creature you can see within 10 feet of you. This damage increases to 6 at 6th level, 9 at 10th level, and 12 at 14th.

But accoring to the rules, a Reaction is in response to a trigger:

Certain special abilities, spells, and situations allow you to take a special action called a reaction. A reaction is an instant response to a trigger of some kind, which can occur on your turn or on someone else's. The opportunity attack is the most common type of reaction.

When you take a reaction, you can't take another one until the start of your next turn. If the reaction interrupts another creature's turn, that creature can continue its turn right after the reaction.

So what exactly are you reacting to? If it is a opportunity attack, does that mean that this Druid threatens out to 5 feet (as opposed to the normal 5)?

It also says it is only in your turn, so I guess you give up your opportunity attack? It still doesn't have a trigger, and seems like it should be a bonus action instead.

Answer 1

Per the description, there is no particular event that the Halo of Spores ability is actually a reaction to. Given that it's an Unearthed Arcana feature, it may be modified to match other reaction-based abilities and thus actually trigger as a reaction to something if/when it's properly published.

This forum post seems to list all the different reaction-based abilities/features. Many are tied to attacks or damage caused by the enemy (or by the character themselves), and some are triggered by nearby allies' abilities, but they do all seem to have some sort of trigger.

That said, even without a specified trigger, reactions work the same way: if/when you use a reaction (which can be on any turn, including yours), you can't use another one until the start of your next turn.

Answer 2

This is one of those cases where specific beats general.

The general rule for reactions is as stated:

A reaction is an instant response to a trigger of some kind, which can occur on your turn or on someone else's.

Halo of Spores introduces a new specific use:

you use your reaction on your turn to deal 3 poison damage to one creature you can see within 10 feet of you.

You can use your reaction without a specific trigger simply because this particular feature tells you so.

It also says it is only in your turn, so I guess you give up your opportunity attack?

Yes - your reaction recharges at the start of your turn, so using this feature prevents you from making opportunity attacks for one round.

It still doesn't have a trigger, and seems like it should be a bonus action instead.

It is probably not a bonus action so you can use your bonus action for other Druid things, like Wild Shape or Shillelagh.

That class feature is all about making the tradeoff of possible high damage (did they provoke? Did you hit when they did?) for consistent low damage (doesn't matter what they do, if you're within 10 feet they're taking 3 damage).

-Speculation follows-

If this is promoted from UA to real material, I would expect the language to change to something like

When a creature starts its turn within 10 feet of you, you may use your reaction to deal it 3/6/9/12 damage

This would preserve the intention of the ability (trade your reaction for guaranteed damage) while making it fall more in line with how reactions are expected to work.

Answer 3

As it states

Halo of Spores

Starting at 2nd level, you can launch toxic spores at other creatures. To do so, you use your reaction on your turn to deal 3 poison damage to one creature you can see within 10 feet of you. This damage increases to 6 at 6th level, 9 at 10th level, and 12 at 14th.

This is saying that if you use this spell, you can't use anything else that uses reactions, such as attack of opportunity.