You might have seen a more complicated variant of this question going on about different types of speed but a comment by Szega made me realize that a much simpler question would probably suffice and that if ever another situation came up where I needed that more complicated answer I could simply ask a new question.

If a familiar spots a hidden enemy, but the corresponding wizard does not, how much time does a familiar need to communicate that danger to the wizard?

RulesI predict to be relevant:

While your familiar is within 100 feet of you, you can communicate with it telepathically.

A member of a group can be surprised even if the other members aren't.

  • 6
    \$\begingroup\$ Could you provide a link to the question you are referring to? \$\endgroup\$
    – MikeQ
    Aug 16, 2020 at 22:14
  • \$\begingroup\$ @MikeQ: Seems to be one the querent deleted (still visible to users with 10k+ rep): How fast is telepathic communication (with a familiar)? Szega's comment was "Is your actual question "Can I avoid being surprised if my familiar is not?"", which I assume is what prompted this simpler question. \$\endgroup\$
    – V2Blast
    Aug 21, 2020 at 9:38
  • \$\begingroup\$ @V2Blast Indeed, It was. His comment made me realize that my question was highly complicated despite probably being only ever relevant in the case of surprise. Other edge cases which might exist - of that I am sure - are simply so unlikely that it wouldn't be worth it to overcomplicate the question. \$\endgroup\$
    – Poseidaan
    Aug 22, 2020 at 7:23

4 Answers 4


Although telepathy the spell operates slightly differently, it's a good place to look for more info:

Until the spell ends, you and the target can instantaneously share words, images, sounds, and other sensory messages with one another through the link, and the target recognizes you as the creature it is communicating with. The spell enables a creature with an Intelligence score of at least 1 to understand the meaning of your words and take in the scope of any sensory messages you send to it.

I think the important detail is even though the communication is instantaneous, it doesn’t mean your wizard's response is. Have you ever had someone ask you a question, responded “what?”, and then within 2 seconds or so processed the question? That is basically the surprised creature's initial response in the first round.

Telepathy even if instantaneous is not appreciably faster than sound for short distances. Sound travels 100ft in 0.09 seconds. Nothing stops an unsurprised character from immediately calling out when there is danger. However, whether that can prevent others from being surprised is entirely up to the gm.

From the combat section of PHB

The DM determines who might be surprised.

Just as importantly is after a few lines.

Any character or monster that doesn't notice a threat is surprised at the start of the encounter.

Noticing a threat is different than being warned about that threat. So for me as a DM, warnings (by voice or telepathy) aren’t enough to avoid surprise unless they are made before initiative.

  • \$\begingroup\$ I had details from telepathy from your previous question. I can pull them out if it’s confusing, but i think they provide further context. \$\endgroup\$
    – Daveman
    Aug 16, 2020 at 18:42
  • \$\begingroup\$ Interesting point that the Telepathy spell only talks about "words", not "ideas". Placing a fully-formed idea of a specific danger could enable faster reaction, but if familiar telepathy works as the spell, that's not an option. However, even placing an image and/or fully-formed words in the wizard's mind could be better than the start of a shout. Communication latency for a whole message isn't just the travel-time latency of the channel (0.0091 sec); it includes the time to transmit the message at some number of syllables per second. That's where telepathy can be usefully faster. \$\endgroup\$ Aug 17, 2020 at 4:47
  • \$\begingroup\$ Its important to realize that there is still an understanding delay. I can show you 500 images in a second, but it doesn't mean you will be able to comprehend them all. \$\endgroup\$
    – Daveman
    Aug 17, 2020 at 12:03
  • 2
    \$\begingroup\$ The familiar can "instantaneously share [...] images, sounds, and other sensory messages with one another through the link," - that is much more than a "watch out", it is "picture of orc". Not only that, but the target can "take in the scope" of the sensory messages. Human reaction speed to (say) a huge boulder landing in the road in front of their car is on the order of 0.1 seconds (some are faster, some are slower). Speaking and parsing language and generating meaning usually takes much, much longer than that. \$\endgroup\$
    – Yakk
    Aug 17, 2020 at 18:04
  • \$\begingroup\$ While you are right that speed of sound is not a limiting factor, you are off with your computations. It takes 0.09s for sound to travel 100ft. Doesn't look like a big difference, but it means that at 1000ft, you can already very easily notice the delay, as it will be almost 1s delayed compared to light. Still, irrelevant for surprise discussion. \$\endgroup\$ Aug 18, 2020 at 8:21

Probably not

  1. There's a difference between communicating with a familiar telepathically and directly perceiving what it sees and hears. We know this, because you can directly perceive with its senses; this requires conscious action on your part and disables your own senses while you're doing it. So it's not as simple as "The familiar sees them, therefore I also see them." It would need to notice the danger and communicate a warning.

  2. A creature in combat can communicate only on its turn, so to warn you the familiar would have to be ahead of both you and the enemy in initiative order:

    You can communicate however you are able, through brief utterances and gestures, as you take your turn.

    The mention of "brief utterances and gestures" makes it slightly ambiguous whether this applies to telepathy, since that form of communication is faster than speech conventionally, but I'd argue that "however you are able" does include all means of communication. There are no explicit mechanics for how communication outside your turn would work.

  3. Mechanically, there's no way to get un-surprised before your first turn. If shouting a warning at someone negated surprise, then everyone would do that, and the statement that "a member of a group can be surprised even if other members aren't" would be untrue in practice.

  • \$\begingroup\$ Telepathic communicatin is faster than talking. But as I puzzle over the question and the answer, that impinges on how the DM determined surprise, which doesn't have the kind of mechanical 'on off' as some previous editions did. \$\endgroup\$ Aug 17, 2020 at 12:51
  • 1
    \$\begingroup\$ @KorvinStarmast I don't think it matters how fast the communication is, just that you're not mentally prepared to act. Suppose you're surprised and you roll low on initiative. The ninja drops out of a tree and tries to stab you. The threat has been pretty well communicated to you, yeah? But on your turn you're still surprised. \$\endgroup\$
    – Mark Wells
    Aug 17, 2020 at 15:52
  • 1
    \$\begingroup\$ The familiar notices the ambush before its turn, in fact before combat. \$\endgroup\$
    – Yakk
    Aug 17, 2020 at 18:02
  • \$\begingroup\$ @Yakk I'm making the usual assumption when neither side is surprised: the familiar becomes aware of the threat at about the same time the threat becomes aware of the familiar (while the wizard is still oblivious). If the familiar is undetected then we really ought to treat everyone else as surprised. \$\endgroup\$
    – Mark Wells
    Aug 17, 2020 at 18:45
  • \$\begingroup\$ @MarkWells I'm saying that the perception check to see if you are surprised in combat does not take place in turn sequence; using turn sequence rules is an error. \$\endgroup\$
    – Yakk
    Aug 18, 2020 at 0:56

You likely won't get the warning in time

Simply put, in order for there to be surprise you must be in combat.

Surprise is a part of Initiative. If you are surprised during the first round of combat, often referred to to as a surprise round in previous editions, you cannot take actions or reactions for the round.

So while the familiar would not be surprised, combat will have already started with the mage surprised. During the familiar's turn, it can use its telepathy to call out, but the mage still cannot act as they are still surprised:

If you're surprised, you can't move or take an action on your first turn of the combat, and you can't take a reaction until that turn ends.

Some DMs may allow the warning to happen, but RAW, you're still surprised.

  • \$\begingroup\$ "communicate however you are able" is listed as "Other activity on your turn" So RAW, the familiar couldn't even attempt to communicate until their turn in initiative, which may be after the wizards. DMs may allow some communication outside of turns, but that is discretionary. \$\endgroup\$
    – Daveman
    Aug 17, 2020 at 1:53
  • 1
    \$\begingroup\$ @Daveman, it wouldn't matter if the familiar's turn was before or after the wizard's. The wizard has already failed their perception and are therefore surprised for one round. So the enemy ambushes the wizard's party starting combat, the familiar sees them but the wizard does not so the wizard is surprised. Regardless of what happens next, RAW, the wizard can do nothing their first round. Except maybe telepathically talk back saying "Too late." \$\endgroup\$
    – MivaScott
    Aug 21, 2020 at 16:38


There's no meaningful difference between telepathic communication and verbal communication in terms of what it allows your character to do. If having an ally shout "Look out!" won't save you from surprise (and it won't), then neither will a familiar's telepathy.

Telepathic communication isn't the same as the "share senses" ability you can activate as an action. If you just happened to have that ability up and running, it might potentially allow you to notice an ambush before it starts, but it's unclear whether you'd share your familiar's successful perception roll or make your own roll using the familiar's special senses (if any apply). In any case, you would be blind to your own surroundings until the start of your turn, which might put you in a bad spot for any enemies who have surprise and beat your initiative.


You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .