I was recently discussing interesting tricks that combat casters can use to control the battlefield, and the following scenario comes up.

The party is defending something against advancing enemies. There's a significant area to cover, so they're having to move about. One party member is a melee combat character with access to magic (we were talking about a Duskblade, because our party has one).

  1. The player readies an action: "when an enemy crosses this line, I will use Dimension Door [or similar] to transport myself to a spot beside them".
  2. An enemy runs across the line.
  3. The readied action triggers, and the character appears beside the running enemy.
  4. The enemy, having not yet finished their move action, keeps running.
  5. The running enemy exits a square now threatened by the character.
  6. The player takes an attack of opportunity on the running enemy.

Is this legal?


3 Answers 3


It is legal, yes.

Note that move actions are defined one square at a time. The running enemy could choose to stop when you teleport in to threaten them. But if they don’t, and leave a threatened square, they provoke from you.

  • 1
    \$\begingroup\$ This. However, if u teleport behind them it'd be pretty crummy if the enemy automatically knew where u were. Maybe a perception check of some sort depending on how distracted they are, what they're doing & which square u need up in. \$\endgroup\$
    – Ben-Jamin
    Commented Feb 18, 2015 at 14:51
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    \$\begingroup\$ I forgot about the per-square move action... although as a DM I'd probably rule that if a character is running, charging, or otherwise moving at speed, they may not be able to instantly halt when someone materialises out of thin air beside them. I'd probably give them a Reflex save with a DC based based on how fast they're going and where the teleporting player appears (ahead, beside or behind). \$\endgroup\$ Commented Feb 18, 2015 at 15:33
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    \$\begingroup\$ For what it's worth, I personally disagree strongly with Ben-Jamin and anaximander. The game abstracts away facing and the like into line-of-sight, which is not impeded, and reaction time into Initiative, which has already been rolled and the “victim” is acting as appropriate for that. In my opinion, throwing an exception to those abstractions in this particular case is inconsistent and complicates matters without benefit for the game as a whole. \$\endgroup\$
    – KRyan
    Commented Feb 18, 2015 at 15:38

Based upon my reading of the spell:

After using this spell, the caster can't take any other actions until his or her next turn.

Although you could do the Dimension Door/Teleport to the location, You could not do an "attack of opportunity" since you can't do anything while recovering from the Dimension Door.

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    \$\begingroup\$ This would preclude any Attacks of Opportunity any time anyone casts a spell. I believe this is a misunderstanding. \$\endgroup\$
    – Wyrmwood
    Commented Feb 18, 2015 at 17:18
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    \$\begingroup\$ @Wyrmwood His point is that Dimension Door specifically precludes any actions until next turn (including immediate actions), unlike most spells. However, Attack of Opportunity does not specify a type of action, just that you can do it, and it clearly isn't immediate because you can still do an immediate action after taking an AoO, so it probably isn't prohibited after casting Dimension Door since it isn't technically an action. \$\endgroup\$ Commented Feb 18, 2015 at 17:33

Yes it is. Remember that it would only take place after the initiative of the character who is readying the action has passed in the turn. If an enemy crosses the line before that character's initiative it does not trigger the readied action.

As KRyan pointed out, the enemy could choose to not leave the threatened space.

To make combat more interesting, the caster could also take someone with them through the Dimension Door

  • \$\begingroup\$ It's both what HeyICanChan and Zachiel pointed out. Players get excited in game and want to ready actions after initiative has been rolled (sometimes before). They can't ready it until it is their turn in the initiative order. They also don't get the attack of opportunity at the time they arrived. They have to wait for the NPC to finish their action which would provoke that attack of opportunity. As you pointed out @KRyan, the NPC could choose not to finish and thus not provoke the AoO. \$\endgroup\$ Commented Feb 18, 2015 at 19:05
  • \$\begingroup\$ @bacrossland: You're right that you can only ready an action on your turn, but I'm quite sure you're wrong about when it triggers. The rules say the readied action occurs before the action that triggers it, and after the readied action completes, the triggering action resumes. The player who had the readied action has their initiative reset to just before the triggering character in the initiative order, but that's very different than the readied action occurring after the triggering action. d20srd.org/srd/combat/specialInitiativeActions.htm \$\endgroup\$ Commented Feb 18, 2015 at 20:46
  • \$\begingroup\$ @MooingDuck Let me clarify to try and clear up the misunderstanding. The squares are W, X, Y, Z (in a row). PC A (square Z) readies the teleport to go square W when NPC B moves into square X from W. PC A has init 15 while NPC B has init 9. Round 1: On init 15 PC A readies the teleport spell. On init 9 NPC B crosses into square X. Before B can cross into square Y, A's teleport goes off putting A in square W. From square W, A threatens square X but not Y. B's turn can now resume. B continues to square Y provoking the AoO from A in square W. Round 2: A's init is set to 10 while B's remains at 9. \$\endgroup\$ Commented Feb 18, 2015 at 21:01

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