Would it be possible to add a condition to check if a specific holiday event is active?

It looks like this would be doable via C_Calendar.GetHolidayInfo(0, todaysday, eventindex) where eventindex ranges from 1 to maxindex and todaysdate is C_DateAndTime.GetCurrentCalendarTime().monthDay and maxindex is C_Calendar.GetNumDayEvents(0, todaysdate)

From there you can just check if result.name matches.

eg. something like:

CONDITIONS["hallowsend"] = {
    handler =
        function (cond, context)
            local currentDay = C_DateAndTime.GetCurrentCalendarTime().monthDay
            local numEvents = C_Calendar.GetNumDayEvents(0, currentDay)

            for i = 1, numEvents do
                local eventInfo = C_Calendar.GetHolidayInfo(0, currentDay, i)
                if eventInfo and eventInfo.name == "Hallow's End" then
                    return true
                end
            end
            return false
        end,
}

I have something like this that I just wrote (it's called "holiday" rather than specifically hallows end). Great minds think alike because your code is quite close, and also I love tickets with code in them! Please send more :)

It should be there in the new beta version 10.1.7-7beta1 if you want to try it out. Getting out a release is a bit tricky at the moment because I'm in the middle of messing everything up to see if WotLK classic support is viable.

Thank you! Yes this is perfect!

Thanks, I'll close this off now. Please log a new ticket if you find bugs.