Is the turn when a readied action goes off, considered a different turn from the one when the ready action took place in?

Question

Is the turn when a readied action goes off, considered a different turn from the one when the ready action took place in?

I'm specifically looking at the Warlock Curse power "per turn"

The Rules Compendium, p.189 on "Once per turn" means you can get the effect more than once in a round, but only once in each turn ...

Some effects can occur only once per turn. If a creature can use an effect (such as a class feature) only once per turn, that effect can be used no more than once during each turn in a round—not only during that creature’s turn.

however I'm not clear ... is the turn the action is readied on, different than the turn the action is actually triggered?, or is it the characters turn just split between the two parts?

Answer 1

Once per turn effects can become eligible for use again on each combat participant's turn (friend or foe), so the main question here (judging by the comments) is if you can use it on an OA and a Readied Action on the same triggering creature's turn. The answer is:

No, Readied Actions do not grant an additional turn for sake of Once Per Turn effects

Opportunity Attacks act as an interrupt to the action they provoke from, thus causing them to exist on the turn of the creature who triggered them.

As for Readied Actions, see this quote:

Immediate Reaction: Using a readied action is an immediate reaction, so it takes place right after the trigger finishes.

So a Readied Action is an Immediate Reaction, now over to this from the Immediate Action rules:

Someone Else’s Turn: A creature cannot take an immediate action on its own turn. The action interrupts some event on another creature’s turn or responds to that event.

This means that a Readied Action happens on the turn of the creature who triggered it. You can use your once per turn effects; however you may still only perform one on that creature's turn. If your Opportunity Attack triggers first and you use a once per turn effect there, it's already been used for that turn and you will have to wait for that creature to end it's turn for you to be able to use it again.

Note that if your Opportunity Attack and Readied Action are triggered by two different creatures, then you're able to use the same Once Per Turn effect on both.

Answer 2

No.

Once Per Round

Some effects are usable only once per round. For example, if a creature uses an effect (such as a class feature) that is usable only once per turn, it can’t use that effect again until the start of the creature’s next turn.

You can only deal curse damage once per turn. The initiative reset has nothing to do with it. A turn lasts from the start of your actions until the start of your next turn.

Using a readied action doesn't give you a new turn, it just moves your initiative. You wouldn't be able to deal curse damage again until your turn is up on the next pass through the initiative order.

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As a thought experiment, consider a standard analog clock where the hour hand is the round and the minute hand is the initiative order. You act at 1:15. You can only deal curse damage once between the time the minute hand reaches you and the time it reaches you again.

When you use a readied action, it's as if you've grabbed onto the minute hand and rode with it until your trigger went off, then jumped off at the new time. It doesn't matter whether it's 1:20 or 2:10 - you couldn't deal curse damage a second time because the minute hand hasn't looped around and given you another natural turn yet.