Two party members—one visible, one invisible—flanking an enemy archer. The invisible PC hasn't attacked the archer, and the archer is unaware of the invisible PC.

The archer wants to take a 5-foot step away from the visible PC so he can make a full attack against the visible PC without provoking attacks of opportunity, but the invisible PC occupies the square the archer tries to step into.

The GM worked around this problem this time, but we'd like to know what the rules say about this situation.

What happens when a creature tries to take a 5-ft. step into a square occupied by an invisible, undetected foe?

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    \$\begingroup\$ Shouldn't the DM know where your invisible PC is and avoid having his NPC archer illegally 5' step into his space? \$\endgroup\$ Nov 11, 2016 at 17:52
  • \$\begingroup\$ @LegendaryDude We don't know the tactical situation. Maybe the PCs were flanking the archer whilst the archer stood in the middle of a narrow bridge? Besides, it may be important to know such a rule in case one day the PC is the archer! \$\endgroup\$ Nov 11, 2016 at 18:05

2 Answers 2


As per RAW:

Accidentally Ending Movement in an Illegal Space: Sometimes a character ends its movement while moving through a space where it’s not allowed to stop. When that happens, put your miniature in the last legal position you occupied, or the closest legal position, if there’s a legal position that’s closer.

Source: Special Movement Rules

So I think that 5ft movement will not happen. Your DM will probably justify that the archer will feel some kind of force pushing him back, and he will then know there is something in that square (total concealment for attacks still applies). Also, you're not entitled to AoO, because a 5ft step doesn't provoke them.

Even if RAW is kinda clear in this case, your DM may rule otherwise. One possible resolution for this action would be the archer initiating an accidental Overrun combat manuever, with some kind of penality.


As a standard action, taken during your move or as part of a charge, you can attempt to overrun your target, moving through its square. You can only overrun an opponent who is no more than one size category larger than you. If you do not have the Improved Overrun feat, or a similar ability, initiating an overrun provokes an attack of opportunity from the target of your maneuver. If your overrun attempt fails, you stop in the space directly in front of the opponent, or the nearest open space in front of the creature if there are other creatures occupying that space.

When you attempt to overrun a target, it can choose to avoid you, allowing you to pass through its square without requiring an attack. If your target does not avoid you, make a combat maneuver check as normal. If your maneuver is successful, you move through the target's space. If your attack exceeds your opponent's CMD by 5 or more, you move through the target's space and the target is knocked prone. If the target has more than two legs, add +2 to the DC of the combat maneuver attack roll for each additional leg it has.

Source: Overrun

The archer would then roll CMB, and receive attacks of opportunity in the process. This may better reflect the situation.

EDIT: Added sources, as per comments request

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    \$\begingroup\$ I've added the sources below every quote in the answer! \$\endgroup\$
    – BgrWorker
    Nov 11, 2016 at 13:07
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    \$\begingroup\$ "Your DM will probably justify that the archer will feel some kind of force pushing him back" ...or he could simply say "you run into someone." Running into an unseen person doesn't feel like hitting "some kind of force"; it feels distinctly like hitting a person. (Ever walk into someone when distracted or moving backwards?) \$\endgroup\$ Nov 11, 2016 at 15:35
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    \$\begingroup\$ The accidental Overrun provoking an AOA nicely recreates the idea of "walking right into it". The rogue was looking for a chance to stick him, and would have done so on his next action, but the opportunity presented itself early. It helps if you remember that one attack roll actually represents an exchange of blows and evasions; it's not one roll = one swing. \$\endgroup\$
    – T.J.L.
    Nov 11, 2016 at 16:21
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    \$\begingroup\$ @T.J.L. And it's sure to make the situation hilarious if the archer manages to win the CMB check and accidentally knock the rogue prone! \$\endgroup\$
    – BgrWorker
    Nov 11, 2016 at 16:39
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    \$\begingroup\$ @BgrWorker Yeah, that's where 5E's Disadvantage mechanic shines. \$\endgroup\$
    – T.J.L.
    Nov 11, 2016 at 16:40

The RAW answer is already covered, the 5' step would fail and they would know that something is there. That's no different to if you run into someone while running backwards and haven't noticed them.

However there is a lot of scope for "rule of cool" here. For example:

DM: The archer is 5' stepping into you, quick what do you do?

Player: I try and dodge out of the way

DM: Ok, acrobatics to try and avoid him (the player gets to move 5')


Player: I drop to the floor and try and trip him over me.

DM: Ok, roll a trip attempt, you get +4 since he's unaware but end up prone yourself.


In other words moments like this are a good opportunity to break from the literal rules and try for a memorable moment. It might come to nothing or it might be the best thing ever and lead to the next year being full of battle cries like "Don't trip over the elf" being shouted at enemy archers.

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    \$\begingroup\$ I think you're correct, but could you clarify what's meant by the 5-ft. step failing? That is, would you rule (or does the game say) that the creature that attempted to take the 5-ft. step into the invisible foe now A) counts as having taken its 5-ft. step despite never having taken that 5-ft. step; B) must either take a 5-ft. step into a different square or stay in its space and counts as having taken it's 5-ft. step; or C) doesn't count as having taken the 5-ft. step and can completely change its mind to take an entirely different action? \$\endgroup\$ Nov 11, 2016 at 17:51
  • \$\begingroup\$ (Not my downvote, by the way.) \$\endgroup\$ Nov 11, 2016 at 17:52
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    \$\begingroup\$ The 5 foot step would be used up but would leave you in your original square as described by bgrworker \$\endgroup\$
    – Tim B
    Nov 11, 2016 at 19:16
  • \$\begingroup\$ I don't even feel this needs to be the rule of cool. I've always permitted the invisible guy to sidestep if they choose to even if it's not their turn unless they're engaged in something that would interfere with that. The notion that he couldn't step aside just doesn't make sense to me. \$\endgroup\$ Nov 12, 2016 at 8:39
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    \$\begingroup\$ @LorenPechtel Actually by the rules he can't, and it does make sense. He's trying to sneak up behind the archer. The archer suddenly steps backwards, he is surprised by that and they bump into each other. If he wanted to be able to step backwards then he would need to ready an action to do so or just stay slightly further away. By doing what you are doing you are giving invisible people an advantage in the action economy. (Not a bad thing as a house rule, but be aware that that is what you are doing) \$\endgroup\$
    – Tim B
    Nov 12, 2016 at 11:04

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