Understanding Attacks of Oppurtunity

[Dysturbed]

Ok so im kinda a new DM and in other games we have played we never had anything like attacks of opportunity.

To my understanding If a character makes a ranged attack or casts a ranged spell. If the target has a ranged weapon he can take a attack of opportunity on the attacker because he opens himself up to attack. This does not count as the original targets attack for the turn it's just a free attack he gets because you foolishly used a ranged attack on him.

Does that attack have to be a basic ranged attack or can it be a power?

The same goes for melee if a character moves around a creature or between two creatures he can evoke attacks of opportunity from both of them. or the one. because he is trying to run past their defenses. This only happens if you try to pass his front squares. the side and back do not count.

Again the question of basic attacks only? Also does shifting count? I assume not since shifting is kinda a way to avoid the front of something but i wasn't sure.

I could be way off of course too.

If a rouge is sneaking around a creature that is 8 squares away from other creature who is looking right at him. The 2nd creature has a crossbow. Does the rouge evoke a attack of opportunity? He is moving withing range of a ranged attack in plain sight. Right?

If there is a good article or something on this or if anyone else can explain it where i can understand it, that would be awesome.

-D-

 

[Aulirophile]

There is no "facing" in 4e. "Back and side" squares have zero meaning. You're aware at all times of your surroundings.

That out of the way:

Opportunity Attacks are Melee Basic Attacks, which is a power everyone gets by default. Some powers can specifically be used as OAs, or MBAs, those are Specific rules which make exceptions to the General rule.

Opportunity Attacks are Provoked by movement when an Adjacent Enemy You Can See Walks, Runs, or Crawls out of a square Adjacent to you. The OA Interrupts the movement, and you attack the enemy before they actually leave the square they were in when they provoked.

Opportunity Attacks are also provoked when an Adjacent Enemy You Can See uses a Ranged Power. It doesn't necessarily have to be an attack. Any Power that says "Ranged" or "Area" is a Ranged Power (Close Bursts/Blasts are not).

Shifting does not provoke OA's because the rules say so. That is kind of the point of Shifting over Walking.

 

[kaomera]

Ok so im kinda a new DM and in other games we have played we never had anything like attacks of opportunity.

What books do you have available? Opportunity attacks are explained several places - in the player's handbook, in the DM's book (the one in the DM's kit), in both of the "Heroes of..." books, and in the rules compendium. If you have a DDI subscription you can also look them up in the compendium.

Opportunity attacks are melee attacks, and unless a creature has an ability (called "threatening reach") it has to be adjacent to a target for that target to trigger an OA (either by moving without shifting or by making a ranged or area attack). (Also: this is the default, feats, powers, etc. might change this.) The OA is a melee basic attack, although again some things can modify that.

If a rouge is sneaking around a creature that is 8 squares away from other creature who is looking right at him. The 2nd creature has a crossbow. Does the rouge evoke a attack of opportunity? He is moving withing range of a ranged attack in plain sight. Right?

As above, he does not provoke an OA from the second creature, because he's not adjacent to it, and if he did it would be a melee basic attack, not a ranged attack. He might provoke one from the first enemy, but if it's not aware of him, or if he's shifting, then he would not.

I can certainly see where it seems like he would, as he's seemingly opening himself up. However, consider that the thief would be dodging around and the creature with the crossbow probably doesn't want to hit his friend - he'll need to wait for his turn to get a shot off.

 

[AbdulAlhazred]

The best article is the combat chapter of the PHB1 or the Rules Compendium.

1) Opportunity Attacks can normally only be taken against an enemy that is adjacent to you, they are usually a Melee Basic Attack, so they would use a melee weapon, not a ranged weapon (but you could do an unarmed MBA and call it whacking someone with your bowstave).

2) Yes, making a ranged attack or an area attack (like a fireball, any power with the range being 'area' or 'range' including Range Weapon. So for instance using the power Twin Strike using a bow while adjacent to an enemy (the target or not) will provoke an OA for each attack made (but note that one enemy can only OA once per character/monster turn).

3) Any number of OAs can be provoked by a single action, as long as each enemy only makes one OA.

4) OAs are never ranged (unless you have some power or something that says different).

5) OAs are never made against anyone that isn't adjacent unless you have a power etc that says different or if you have Threatening Reach (very hard for PCs to get). Only a few monsters have this. It lets them OA at greater distances, but it is still a melee attack, not a ranged attack.

6) There is no such thing as facing in 4e, so you technically can't sneak up behind an enemy once combat is joined. A rogue (for example) can sneak up on a monster IF he has cover and can make stealth rolls that beat the monster's passive perception (most up to date stealth rules are in the RC or PHB2). You can 'jump out' at someone and gain combat advantage, but it lasts only during the single action you come out, so your action better be both a move and an attack (charge or certain powers that combine movement and like Deft Strike).

7) Shifting, teleporting, and being force moved don't trigger OAs, so any character can shift 1 square safely but some powers/class features/etc do allow OAs against shifting in some situations. Teleporting or being pushed, pulled, slid are pretty much always safe. Invisible and hidden characters will also avoid OAs.

8) Note that there are couple of things a creature must be able to do in order to take OAs. It has to be able to see you and it can't be stunned or dazed.

Mostly I think carefully reading the Rules Compendium combat chapter and playing through some scenarios will help you understand it better. You'll want to pay attention to the rules on what actions you can take at what times and the stealth rules, and also Line of Sight, which are all pretty interrelated in an actual fight. Make sure to get an idea of what all the conditions do as well.

 

[Aulirophile]

Ah, left out Threatening Reach. Yeah, TR is an exception: if you do any of those things within the Melee Reach of a creature with TR it provokes. If a creature has TR it'll be noted in the stat block.

Oh, since you're a DM this is relevant:

See that? If a power in a Monster's Stat Block has that symbol next to it, it is that Monster's Melee Basic Attack. So if your players provoke an OA from a Monster you use that power. Some Monsters don't have an MBA power listed. Technically you can look at their Str, and make an Improvised Weapon Attack, but it isn't really worth bothering.

 

[Dr_Ruminahui]

Only 1 final comment - a creature cannot take opportunity attacks (or any kind of opportunity actions on its own turn).

For example, lets say we have a knight. He has an aura that lets him take an opportunity action (which gives him an attack) against adjacent monsters when they shift.

On the knight's turn, he hits the monster. The monster has a power that lets it shift when hit by an enemy, and uses it. The knight would not be able to use his own opportunity attack power (even though it is triggered by a monster shifting), as the shift is on his turn.

 

[Tony Vargas]

Does that attack have to be a basic ranged attack or can it be a power?

Any ranged or area power provokes (it doesn't even have to be an atttack - a ranged or area utility would provoke, too). There is no difference, in that sense, between an exploit, spell, or prayer. (Unless it specifically says it doesn't - probably in a 'Special' line.)

Note that 'Area' has a specific meaning. A 'Close' power (though, like an Area, it affects a Blast or Burst) does not provoke.

Technically, a 'ranged attack' provokes, too, but there are vanishingly few attacks that are not also powers, even if that power is just 'Ranged Basic Attack.'

This only happens if you try to pass his front squares. the side and back do not count.

There is no facing. Creatures do not have a specified 'back' or 'side.' A creature can make an OA against a provoking enemy in any square adjacent to it.

Again the question of basic attacks only?

Yes. Though there are attack powers that can /specifically/ be used to make Opportinuity Attacks.

Also does shifting count?

No. Shifting does not provoke.

If a rouge is sneaking around a creature that is 8 squares away from other creature who is looking right at him. The 2nd creature has a crossbow. Does the rouge evoke a attack of opportunity? He is moving withing range of a ranged attack in plain sight. Right?

Movement only provokes OAs from /adjacent/ enemies. Even if an enemy has reach, such as with a longspear, he can only take an OA if you are adjacent.

(Again, there is an exception: some monsters have a trait called Threatening Reach, that lets them OA enemies w/in their *melee* reach.)