Is there any reason to delay an action?

[With a box]

Delay (http://www.d20srd.org/srd/combat/specialInitiativeActions.htm)

By choosing to delay, you take no action and then act normally on whatever initiative count you decide to act. When you delay, you voluntarily reduce your own initiative result for the rest of the combat. When your new, lower initiative count comes up later in the same round, you can act normally. You can specify this new initiative result or just wait until some time later in the round and act then, thus fixing your new initiative count at that point.

You never get back the time you spend waiting to see what’s going to happen. You can’t, however, interrupt anyone else’s action (as you can with a readied action).
Initiative Consequences of Delaying

Your initiative result becomes the count on which you took the delayed action. If you come to your next action and have not yet performed an action, you don’t get to take a delayed action (though you can delay again).

If you take a delayed action in the next round, before your regular turn comes up, your initiative count rises to that new point in the order of battle, and you do not get your regular action that round.
Is there any sane reason to sit back and do nothing in combet?

[Vizzerdrix]

Yes.
Setting up for sneak attack.
Letting the casters set up some control or nuke the chaff.
Waiting to see who the BBEG hit to drop a heal.
Timing for counter spells.

[Grod_The_Giant]

Wait for the casters to buff you before attacking
Wait for the enemies to come into range before charging
Waiting for the wizard to fire off his big area spell before entering melee

I could go on. Basically, there are lots of times when you'd prefer to go after another member of your party.

[Curmudgeon]

Setting up for sneak attack.
I think what Vizzerdrix means is waiting for one of your allies to engage an enemy in melee combat, then getting into a flanking position opposite that ally. Flanking enables sneak attack.

Lots of people keep suggesting Improved Initiative as a good feat for Rogues. I think it's a terrible feat, because you'll just end up Delaying longer waiting for your allies to get into position.

[PlatinumVixen]

I've pretty often used delayed actions for ambush attacks as ranged characters.

[Vizzerdrix]

I think what Vizzerdrix means is waiting for one of your allies to engage an enemy in melee combat, then getting into a flanking position opposite that ally. Flanking enables sneak attack.

Yeah what he said.

[PaucaTerrorem]

Any enemy that hasn't acted in the first round is considered flat-footed.

[nyjastul69]

Any enemy that hasn't acted in the first round is considered flat-footed.

Which means that the opponent will probably be denied their dex to AC. That's the important bit for SA, flat-footed is actually irrelevant.

[Sith_Happens]

As a caster, to wait and see if you really need to cast that last spell or if your teammates are about to finish off your target anyways.

As a Warblade or Crusader, to use White Raven Tactics on someone you rolled higher initiative than.

[Eloel]

Lots of people keep suggesting Improved Initiative as a good feat for Rogues. I think it's a terrible feat, because you'll just end up Delaying longer waiting for your allies to get into position.
Unless you're unable to attack at first round, this doesn't hold much water.

[thecrimsondawn]

Well on the subject of Rogues and imp initiative vs holding an action,
Sure, a rogue with there often crazy dex with that feat will have something like +9-15 on there roll to see who goes first, but that means that the surprise round did not happen more often then not. That means that your rogue is now in the middle of enemy lines, maybe even surrounded, and in a very bad place since your casters cant aoe as well now as they may hit you. While ranged sneak attack is an option, (deepwood sniper comes to mind if I remember right) Rogues are often played best observing the situation and making tactical decisions to make "sure" the battle goes the parties way.

This play style at least involves a whole lot of action holding, or positioning, otherwise you will just be the corpse :P

[SangoProduction]

There's also an oft not used method (Although I think this is holding action rather than delaying, but really they should be the same thing): waiting until your opponents declare an attack, or move. This way you can decide "Do I want to fight defensively, or strike with reckless abandon, because they aren't going to attack me?"

[Andezzar]

Timing for counter spells.Counterspelling does not work with delay action. You need ready action for that.
Delay action only lets you set your initiative check to a certain lower result. Delay action even explictly prohibits interrupting:
You can’t, however, interrupt anyone else’s action (as you can with a readied action).
So you will either act before or after the caster. Neither works with counterspelling.

[Curmudgeon]

Unless you're unable to attack at first round, this doesn't hold much water.
OK, then, explain how Improved Initiative is good for a Rogue.

In the surprise round the Rogue isn't surprised because of maxed Spot skill. Wielding a bow, the Rogue gets to pick among various flat-footed opponents, and adds sneak attack damage to one ranged attack.

In the first regular round of combat the Rogue continues to choose among flat-footed opponents, adding sneak attack damage to every shot of their ranged full attack. Having good DEX boosts initiative some. It's not necessary to act particularly early; it's only necessary to act while there's at least one enemy still flat-footed.

In the second regular round of combat the Rogue no longer has flat-footed enemies, so it's time for flanking. If there's already an ally engaging an enemy in melee, the Rogue can move to a flanking position and get one melee attack with sneak attack damage added. If allies have worse initiative and haven't closed for melee combat yet the Rogue can Delay.

The difference in d20 rolls could be up to +/- 19, and +4 from Improved Initiative isn't nearly enough to offset really bad rolls. Nearly all of the time the Rogue gets to add sneak attack damage without needing Improved Initiative.

[Zaq]

It's not necessary to act particularly early; it's only necessary to act while there's at least one enemy still flat-footed.

If your goal is just "get Sneak Attack on someone, anyone," then sure, that works fine. If your goal is "get Sneak Attack on specific high-priority targets, hopefully focusing fire with the rest of the party," then the higher your initiative is, the better chance you have of being able to target the best possible enemy.

Rogues are feat-starved enough that I'm not going to argue that Improved Init is a fantastic use of a feat (it takes a very restrictive book environment for it to be the best possible use of a feat slot, more often than not—we're not in disagreement there), but it's still in your best interest to go as early as you can and therefore to get your pick of whatever target you like. This is usually handled better by init-boosting items than by init-boosting feats, but still, Improved Init does have enough of an effect that I wouldn't look down on a Rogue for taking it, even if I don't think it's necessarily the strongest choice for a feat.

[Bruenin]

You can delay so you can go sooner in the initiative order, you just pick where you want to be in the initiative order, but to delay to a spot earlier than your original one you effectively have to give up your turn and then you start your next turn at that new initiative position. You keep that place unless there's another change in initiative from someone delaying or whatnot. I don't know much utility you can get from that but it's always an option.

[Firechanter]

* Waiting for the enemies to enter your threatened area and draw some AoOs, _then_ using your own action to full-attack these enemies.
Rather than spending half your turn to move into range, attack a single enemy once, then have the enemies attack you without drawing any AoOs.

[nyjastul69]

* Waiting for the enemies to enter your threatened area and draw some AoOs, _then_ using your own action to full-attack these enemies.
Rather than spending half your turn to move into range, attack a single enemy once, then have the enemies attack you without drawing any AoOs.

Entering a threatened area doesn't provoke an AoO, leaving one does.

[Firechanter]

Sure, but you know what I mean. ^^

[LooseCannoneer]

I delay and ready actions (readying all of your actions is better than delaying, in my opinion, because you can interrupt enemies if you word it right) all the time. Standoffs lead to great readied actions.

[Andezzar]

I delay and ready actions (readying all of your actions is better than delaying, in my opinion, because you can interrupt enemies if you word it right) all the time. Standoffs lead to great readied actions.You can only ready a standard or a move action. All your actions can only be delayed.

[atemu1234]

Entering a threatened area doesn't provoke an AoO, leaving one does.

Wonder how that works IRL.

[Andezzar]

It does not. The world is not divided into 5 ft squares.

[Elder_Basilisk]

I think what Vizzerdrix means is waiting for one of your allies to engage an enemy in melee combat, then getting into a flanking position opposite that ally. Flanking enables sneak attack.

Lots of people keep suggesting Improved Initiative as a good feat for Rogues. I think it's a terrible feat, because you'll just end up Delaying longer waiting for your allies to get into position.

You could charge or otherwise get sneak attack for attacking a flatfooted foe. For reasons other people mentioned (being surrounded by bad guys without the fighter types to distract them) this is often a bad idea. However, if you have Spring Attack, a reach weapon, or another mechanism of limiting your exposure to being swarmed, it can still be a good plan. That is even more true if you are a multiclassed rogue and your defenses are basically indistinguishable from the fighter or barbarian.

Another way that rogues can take advantage of high initiative/flatfooted foes without risking being surrounded is to get their high initiative start of combat sneak attacks on ranged attacks. A rogue with a shortbow (or a longbow+rapid shot if they took a two-level dip into ranger) in hand (or a dagger (returning if you want to use it in melee next round) can drop sneak attacks on flatfooted enemies from range then move into the flank with the fighter type on the next round.

Also, WRT Improved Initiative, while it doesn't necessarily mean you will win if you roll a 1 and the opponent rolls a 20 (1/400 chance), it is roughly similar to rolling twice and taking the better result if you and your opponent would otherwise have the same bonus. If I recall my D&D minis days correctly, I think they both work out to a 66-75% chance of winning initiative against that one foe. In ordinary D&D/Pathfinder, where (at least RAW) every foe rolls init separately, it will have a pretty significant impact on your chance of beating every foe on initiative too though there are too many variables (number of opponents, their initiative mods, your init mod, etc) to reduce it to a single number. Mathematically, however, your odds of beating everyone go down exponentially with the number of opponents so small numerical increases in your individual odds have a major impact on reducing that decrease. It should function much the same way that your odds of making all of your "make or break" saving throws (which you really want to do) go dramatically down when you start failing them on a 2 and each increment they decrease has an increasingly detrimental impact on your odds of making all your important saves.

[Eloel]

It does not.
Not with that attitude.

[Curmudgeon]

Another way that rogues can take advantage of high initiative/flatfooted foes without risking being surrounded is to get their high initiative start of combat sneak attacks on ranged attacks. A rogue with a shortbow (or a longbow+rapid shot if they took a two-level dip into ranger) in hand (or a dagger (returning if you want to use it in melee next round) can drop sneak attacks on flatfooted enemies from range then move into the flank with the fighter type on the next round.
Yes, that works. It also works without Improved Initiative. With the bonus from the feat (+4) much smaller than the dice variation (+/- 19), there's not much chance that II will make the difference to let you attack some particular foe when they're still flat-footed. Instead, you might get one random extra flat-footed target to choose among. Because you're not going to get ideal choices all the time, the feat (to my mind) isn't worth taking. You'll almost always get some choice of flat-footed foes with or without the feat, and dealing enough extra damage to kill some enemy muscle before they've got a chance to act (because you've got Craven instead of Improved Initiative) is better than a small increase in the chance of being able to damage (but probably not kill) the ideal target.

[nedz]

It depends upon the game, or situation.

If encounters are ambushes (on the party), or simple meeting engagements, then delaying is rarely useful.

If encounters develop over a number of rounds then delaying may be useful since more information will be available if you wait before you act.