I recently created a homebrew spell which, among its other language, lasts
until the start or your next turn or until you take another action or are incapacitated.
My question is, would the caster taking any reaction end this spell early. Mostly I'm curious as to if there's consensus as to how such a rule would be interpreted.
In other words, “homebrew problems require homebrew solutions”. One of the things I’ve implemented into the review process of my own homebrew is checking for sentences with the potential for confusion, and then being okay with expanding those sentences to be more explicit. I get that there is a certain appeal to succinct and neat writing, but unless you are writing for publication, I think there is much more value in being clear about what you want a feature to do at the cost of using more words.
To this end, if you want a reaction and bonus action to end the spell, just rewrite that sentence so:
until the start of your next turn, until you are incapacitated, or until you take another action, reaction, or bonus action.
In contrast, if you only want a proper action, not a reaction or bonus action, to end the spell, just write that into the sentence:
until the start of your next turn, until you are incapacitated, or until you take another action (but not bonus action or reaction).
It’s more words, but the potential for confusion is attenuated.
It wouldn't end the spell.
Other conditions that prevent you from taking actions (like Incapacitated) specifically call out that you can't take "actions or reactions", which shows they're not the same thing, and it's possible to deny one while not denying the other.
