In a pbp game I am DMing a player readied an action with his bow using the following condition: ''He pauses, waiting to see if the halfling will try to cast a spell so he can disrupt it, otherwise he will just shoot him if makes a move to do something else."
The halfling had drawn a potion the previous round and drank it during the round he was targeted by the player's readied action. When I posted an update on the combat I said that the character watches for the halfling to cast but he didn't cast a spell so the character loses his readied action.
So, the above is just a little background for my actual question: Is a general ready action such as the above (i.e. I'll attack if he takes any sort of Move or Standard action) a valid condition for the Ready an Action action or is a more specific condition required?
To me, a readied action does not mean the character loses all perception of the world around him. He's watching the halfling with (albeit poorly phrased) intent to disrupt the halfling's next action. The character would see the halfling lift the potion flask, and could then fire his arrow to disrupt that action, just as the halfling commencing a spell would allow him to disrupt that action. If the halfling does nothing, or seems to do nothing (concentrates on an existing spell, casts a Still and Silent spell, delays or readies his own action), and the character's initiative rolls around again, he's still waiting for the halfling to do something, so he loses the readied action.
The character basically has three choices when his initiative comes up. He can take an action, ready or delay. This character has chosen no action, so he can ready or delay. The advantage of delay is that he can watch the flow of the combat, and decide how to act when he sees fit. Maybe that's against the halfling, or maybe it's against another target, or he moves to support a teammate in melee, or he does any of a dozen other things.
The advantage of a readied action is speed. He can't take action against anyone but the halfling, but he can take action rapidly enough to disrupt a spell, knock the potion from his grasp or strike him as he draws a weapon. The drawback is flexibility - he's focused on the halfling so he doesn't have the luxury of changing his mind to attack the half dozen orcs that suddenly burst through the door behind him.
"I shoot the man if he searches the fireplace, but only if the fireplace has no secret compartments," could work, but that means the search is completed before he fires. It should also be restated "only if he finds no secret compartments", as a failed search doesn't mean there are none, only that the man stopped searching before finding one. He can't retroactively shoot at the start of the search after the fellow finds nothing.
"I will shoot the man if he comes by, but only if he is not tarrying or running, nor singing. Also, he can't seem to be making apple pies. But only if he's not talking about sports. He can have neither have sombreros nor stilts. He cannot be an acrobat. I will not shoot if he has no expression as he doesn't dally to the west," seems ridiculously complicated. However, he could wait to shoot a member of a specific race, a person of a specific height range, or even "The Chancellor" (what do you think an assassin laying in wait does? He Readies!). He could require the Chancellor be alone, and will not shoot if he's talking, for fear of alerting some nearby guard.
But if the Chancellor is disguised, and that disguise fools our Assassin, he does not fire, since the terms of his action have not, to him, been met. If the person with him is invisible and undetected, he will still fire as the Chancellor seems, to him, to be alone.
To borrow a catch phrase from the developer of a different game system, "apply your common and dramatic sense".
