Using a Readied Action to avoid Opportunity Attacks

Question

In 4E, combatants can't take Opportunity Actions (OAs) and Immediate Actions (IAs) on their own turn. Some Defenders function by getting to make OAs or IAs whenever the enemy attacks or shifts. This makes them "sticky" in that it's hard to get away from/past them without getting smacked (and often times that cancels the movement).

So the following trick came to mind, for an attacker to get past/away from a Defender: The attacker readies an action to move/shift/charge/attack-an-adjacent-squishy as soon as it becomes the defender's turn. That way the defender can't use OAs.

1. Is that a legal condition for a readied action, or does the condition have to be something concrete and visible done by the defender? e.g. "the defender moves, or attacks, or uses any power"?
2. Would the trick work as I'm envisioning it? It seems like both the PCs and the mobs could use it.
3. What are the downsides of using this? Obviously you give up your Standard action, which is a high price to pay if you were only going to use a Move action to walk or Shift. It also shuffles you around in the turn order. Anything else I'm missing?
4. Are there any easy counters to it? I see:
   • Doubling up Defenders would ensure that at least one Defender's OA can function.
   • The Defender could choose for the first action of its round to be readying an action to intercept the attacker. In that case it wouldn't be an OA (but that has upsides and downsides). Edit this won't work; readied actions can't take effect during your original turn.
   • The Defender could Delay until the attacker's next turn, denying them the Readied Action -- but this requires that the Defender know that the attacker is trying this.

Or am I completely off-base here? Does some rule prevent this trick?

Answer 1

Ready an Action

Action: Standard action. To ready an action, a creature follows these steps.

1. Choose Action to Ready: Choose the specific action the creature is readying (the attack it plans to use, for example), as well as the intended target, if applicable. The creature can ready a standard action, a move action, or a minor action. Whichever action is chosen, the act of readying it is a standard action.
2. Choose Trigger: Choose the circumstance that will trigger the readied action. When that trigger occurs, the creature can use the readied action. If the trigger doesn’t occur or the creature chooses to ignore it, the creature can’t use the readied action and instead takes its next turn as normal.
3. Immediate Reaction: Using a readied action is an immediate reaction, so it takes place right after the trigger finishes.
4. Reset Initiative: When the creature finishes the readied action, its place in the initiative order moves to directly before the creature or the event that triggered the readied action.

You have to call the triggered action

IN 4e you have to be fairly specific, for example, "I ready my bow to shoot the first creature who steps through the door" or "I attack this goblin if he tries to move or attack anyone else" you can't say generally "I will shoot any monster I see" if that makes sense.

When a readied action goes off your initiative moves to that slot

By attacking the creature "on the start of its turn" you effectively come in before the start of its turn because its turn cannot be split between before you attack and after. Would hypothetically resolve as their turn began but then your turn would be moved to before hand.

The Semantics Rub

Turn

On a creature’s turn, it takes actions: a standard action, a move action, a minor action, and any number of free actions, in any order it wishes. See also once per turn.

Because the creature has taken no actions yet, its turn in truth hasn't begun even if you are triggering on the start of their turn, I'd say that they'd still get an op attack.