Dungeons & Delvers: Opportunity Attacks

Over on the Facebook RPG Design Network, someone was asking about opportunity attacks and how he should implement them in his game.

This, heh, provoked a bunch of responses, most of which were telling him to just not bother for several reasons, ranging from an action economy to confusion as to why you would get to do something out of turn.

One guy claimed that it's too difficult to remember everything that provokes opportunity attacks.

Now this is something I agree with, but only in the context of 3rd edition Dungeons & Dragons, where there was almost an entire page plastered with tables, listing I think every possible action and whether it provoked an attack of opportunity.

4th Edition pared this down to moving from one threatened space to another (unless you were shifting), ranged attacks (including bows and spells), and area attacks. Close blast and burst spells were cool, as were spells that also qualified as melee attacks (there was a feat that turned your magic missile into a melee attack).

5th Edition ditched every trigger except movement, but only if you left an enemy's threatened area; presumably you can move around an enemy without provoking an opportunity attack. The exception to this is if you take the Disengage action, which lets you book it without getting hit. Spells no longer trigger them, and ranged attacks are made with Disadvantage.

Really if you want to speed things up and avoid confusion, just trim the list. Keep it simple. Only like 1-3 things in total.

As for being unable to do anything outside of your turn, I posited a very simple question: a fighter kills a goblin on his turn, then another goblin tries to run past the fighter. The fighter isn't otherwise occupied, so why wouldn't he be able to attack this goblin if he tried to run past?

As of this blog post I haven't received an actual answer from anyone. One guy tried to argue that if a fighter can attack this one goblin, that he should also be able to attack five separate guards each trying to get past him. I asked him to explain how attacking one target while unoccupied is the same as attacking five targets in rapid succession, but he just blocked me.

A, uh, reasonable response, I'm sure.

One of the stranger reasons was based on the misconception of opportunity attacks not having a "cost". As in, there's no drawback, so there's no reason not to make an opportunity attack if the, well, opportunity comes up.

It's been awhile since 3rd Edition, but in both 4th and 5th Edition opportunity attacks key off of either an Immediate action or Reaction respectively. In 4th Edition there was both an Immediate Interrupt and an Immediate Reaction, and using either prohibited the use of the other for a turn. In 5th Edition you only got a single Reaction per turn.

Turns out besides readied actions both editions feature a number of abilities and magic item effects that use these up, too, so if you choose a power, paragon path, or subclass that gets these, or obtain magic items that use them, you'll need to keep that in mind. Of course, it might not matter much since there's always specific criteria that triggers opportunity attacks anyway: you can't just accidentally blunder into one.

The thread petered out in a couple days, and my takeaway based on responses (or lack thereof) was that opportunity attacks make sense, and based on 4E and 5E can both be very simple to implement and have a meaningful cost, so here's how they're going to work in Dungeons & Delvers: Red Book.

To keep things simple, they're primarily going to trigger off of movement: if someone tries to run past you, or tries to run away from you, you can try to get a hit in.

They use up your Reaction, which aside from triggering readied actions includes a variety of abilities that have been around since Black Book and Appendix D: some aspects of dual-wielding, for starters, as well as other talents that give you a kind of counter attack if someone misses you (Shield Bash, and the rogue's Feint).

There are also a variety of Reaction talents that force an enemy to re-roll their attack and use the lower result, such as the rogue's Evasion (which also lets you run away if the attack misses). Really most classes have some way to use a Reaction, and while in many cases you have to choose talents to pick them up they're pretty good (especially if you're playing a squishier class).

There's another restriction: you cannot make an opportunity attack if you're currently engaged with another enemy. As in, actively fighting them in melee combat.

It's kind of like a condition, or a status or state that you don't really think about unless enemies are trying to run past each other or flee. The reasoning is that while engaged you're too focused on not getting stabbed, or looking for an opening with your current opponent to really pay attention to much of what's going on around you.

And that's it. We think that's really all it needs to do, but are considering having ranged attacks trigger them, too. Maybe even spells, though we don't want to make too many exceptions or specifics. We want mechanics that make sense in-game, but not at the cost of having to consult a big-ass list or table.

You can now get a physical copy of Dungeons & Delvers: Black Book in whatever format you want! We've also released the first big supplement for it, Appendix D, so pick that up if you want more of everything.

The first issue of The Delver, a magazine featuring fungal-themed content for both players and GMs (including an adventure in which myconids find religion), is available!

Our latest Dungeon World class, The Ranger, is now available.

Dwarven Vault is our sixth 10+ Treasures volume. If you're interested in thirty dwarven magic items (including an eye that lets you shoot lasers) and nearly a dozen new bits of dungeon gear, check it out!

By fan demand, we've mashed all of our 10+ Treasure volumes into one big magic item book, making it cheaper and more convenient to buy in print (which you can now do).


  1. Who changes engagement, the attacker or the defender? Or both? If on my turn I attack goblin A in melee, and then goblin B attacks me in melee, which of them am I engaged with? Can you be engaged with more than one enemy, if you use multiattack to attack two or more targets?

    1. @Conner,

      Oooh good questions!

      A creatures can only engage with one target at a time, but a creature can be engaged by multiple creatures.

      Attacker is engaged with the last creature that he attacked (since you opted to focus on them). When attacked you can opt to effectively change your focus, considering yourself engaged instead with your attacker.

      Example of one fighter and two goblins:

      Fighter attacks Goblin A, he is now engaged with that goblin. Goblin B can opt to attack and engage with the fighter, or do whatever. If Goblin B attacks, the fighter can opt to pay attention to that Goblin, or keep focusing on Goblin A.

      If he switches to Goblin B, then Goblin A can now run away, no problem, or do something else. Of course if Goblin A seems much more dangerous the fighter can choose to keep his attention on that Goblin, leaving Goblin B free to run away.

      I figure this will be used somewhat strategically, with party members trying to draw a monster's attention in order to let another PC get away without getting their butt kicked. Have to add some GM advice so things are logical in-game.

      Could see talents and maneuvers that rely on the Engaged status, but don't want to muck things up TOO much.


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