Is it possible to fool an animal companion impersonating its owner? For example, if a druid is fighting with his party and its animal companion - let's say a wolf - would its opponent be able to get the wolf attack an ally of the druid imitating the druid's voice?
If it is possible, how can it be done? Is a skill check on Handle animal or Bluff a good way?
At least unless it was agreed upon on session 0 or was included into your "social contract" in a clear way.
Animal Companion is a class feature. Making it work against the character removes his agency over his own class features. This does not sound right, does it? Mind control spells are something that many tables ban outright, and most tables use sparingly. It is one thing if enemy prevents something from working (like counterspelling Fireball), it is totally another if he makes it work against the player (like making fireball turn around and hit the caster).
Handle Animal works on Animal Companion all right, as explored in more detail here. But it uses does not include fooling animal. This skill is limited to:
Nothing here about pretending to be an owner.
Bluff requires interaction. Faking master's voice can do the trick. Note, that:
Two circumstances can weigh against you: The bluff is hard to believe, or the action that the target is asked to take goes against its self-interest, nature, personality, orders, or the like.
Animal could get Sense Motive bonuses of +20 for too incredible to consider (wrong smell and clothes) +10 for putting it in danger, total +30 on top of its natural bonus. A bit too high to be reasonably considered.
Perfectly reasonable uses would be:
Feinting in Combat
You can also use Bluff to mislead an opponent in melee combat (so that it can’t dodge your next attack effectively). To feint, make a Bluff check opposed by your target’s Sense Motive check, but in this case, the target may add its base attack bonus to the roll along with any other applicable modifiers.
Creating a Diversion to Hide
You can use the Bluff skill to help you hide. A successful Bluff check gives you the momentary diversion you need to attempt a Hide check while people are aware of you. This usage does not provoke an attack of opportunity.
Disguise is the main skill for "I'm that man" type of play. Still, Animal companion would get Intimate +10 familiarity bonus to counter it.
Successful Disguise check plus successful Handle Animal (push) check could work. "the animal performs the task or trick on its next action" part would give the Druid a chance to counter it before it happens, though. And said checks would be hard.
Successful Bluff could create confusion that would let you stab said animal more effectively, or hide yourself, but that would be the limit I would put, as this is both my understanding of the rules, and, in my experience, border of what my players would still find fun and interesting.
Unlike paladins’ special mounts or mages’ familiars, druids’ animal companions do not have an “empathic link” special feature that allows them to feel their (true) master’s emotions in a continuous way—that would probably be a dead giveaway.1
However, the animal companion and druid do share a “link” of an unspecified nature, that allows the druid to more easily handle the companion. Mechanically, this is represented as a bonus on Handle Animal plus the ability to use Handle Animal more swiftly (lower action cost). Narratively, we aren’t given a lot of description, but if the companion is more resistant to the impersonator’s handling than they would normally be with their master, that would be a large clue. Animal companions retain animal intelligence, and we don’t know how obvious it is to the animal that something is off—but real-life animals tend to be pretty sensitive to that kind of thing as it is, and the druid has something special and more than that with their companion. And it’s not something that you can easily overcome—even if your Handle Animal bonus is greater than the druid’s, so you can’t tell that the +4 bonus is missing, the extra time it takes to handle a non-companion animal can’t be worked around. So the companion must know something.
If it were possible at all—and ultimately that’s going to be up to the DM, we aren’t given enough information on the link to say for sure—it would be very difficult and very easy for situations to make it outright impossible. The less the impersonator tries to handle the companion, the better—but that might not work out so well if the true master is in the habit of handling the companion pretty frequently (which most druids are, since they’re directing the companion in combat). Bluff and Disguise are crucial, but they may not be enough. For example, without real polymorph magic, you almost-certainly cannot replicate the druid’s smell—and many animals are going to rely more on that than they will on whatever you look like. Even for more visual animals, the way they see the world is different from ours, their eyes are physically and biologically different—the details they rely on for recognition may well be literally invisible to humans. If that’s the case, it would be impossible to produce a convincing disguise, because you can’t even sense the distinguishing features that would make it convincing.
In short, personally I’d be pretty dubious about this working. As a DM, I might allow you to try if you used extremely exacting polymorph magic, and it might work for a time, but I expect the animal companion to pick up on extremely small differences and react strongly to them.
