How does true polymorph work with the companion from the rangers beast master and warlocks pact of the chain class options?

Beast Master

  • Can it be true polymorphed into a large CR 1/4 creature?
  • Can the beast companion be polymorphed into a huge rock and then into a t-rex by a second caster?
    • Can this be taken further and be polymorphed into a young gold dragon?

Pact of the chain

  • Can a familiar be polymorphed?

There are a few points I can see with each for both sides.

The beast master subclass stipulates that you can only bond with a medium or smaller CR 1/4 or lower beast, however, does this mean that if your beast were to be effected by an enlarge spell, would it stop being your companion? I can't find anything that would be grounds for your beast to leave you/stop being your companion beyond death (which is only implied). If How do multiple castings of True Polymorph interact? is to be believed, would your beast still be considered your companion after the first true polymorph into a huge rock?

For the pact of the chain, can a familiar (spirit in the form of a creature) be true polymorphed? While it technically shapeshifts into the form you choose, the creature it exists as is not a shapeshifter and it cannot change it's form after being summoned. If it can be polymorphed, would it stay polymorphed when it is sent to its pocket dimension because at this point, you can choose a new form for it.

In both cases, I feel that it should be possible considering that the loyalty and or binding is either the mental state of your beast or your stat, both of which are not effected by true polymorph. While this may be considered rule lawyering, remember that if players are doing this, they must have at least two 17th level PCs or have a DM that will allow them to get the spell casting service from NPCs earlier in the game. This would cost roughly 1620 GP per companion (NPC spell casting services cost Square of the spell level multiplied by 10 gp plus DOUBLE of the consumed material cost plus 10% of nonconsumed material cost).


1 Answer 1


here are my thoughts as a 5e DM for over a year for a full party of rules lawyers

permanent not instantaneous

The point to recognise here is that concentrating on true polymorph makes the spell permanent not instantaneous and hence the spell remains in effect and is dispellable after concentration has completed.

In this circumstance, we get to the situation where we have two of the same spell in effect in which case the rules for combining spells come into effect.

""" ...different effects add together...The effects of the same spell cast multiple times don't combine ...the most potent effect ... applies while their durations overlap. """

it would be likely up to DM discretion as to whether there is a more potent effect in becoming a TRex vs becoming a Rock. Obviously the TRex is more useful though.

Even ignoring that and assuming TRex conversion is more potent, going from familiar to rock happens first and then once you are a rock (assuming you are a big enough rock (below)) you become a TRex.

as soon as the duration of TRex activates, the duration of rock deactivates (regardless of whether it has been made permanent). This means one of two things:

  • your familiar is no longer eligable to be polymorphed into a TRex as it is a creature of CR 1/4 or less
  • the duration of rock transform must become instantaneous to accomodate the casting of another true polymorph.

I consider the first case the most likely as there is nothing to suggest that a polymorph is or can become instantaneous nor do the rules suggest that such a thing can occur to facilitate sequence casts and further it seems in line with what I read as the intention of the spell (given there is a separate option for creature to creature anyway). If the second is chosen by your DM (or you if you're the DM) the natural consequence of this is that the familiar is now actually a rock and so casting dispel in effect 'kills' your familiar (though it's really more like stasis for them)

caveat: a polymorph by any other name

given that the rules specify that the same spell multiple times doesn't combine but different spells do; one might argue that any other spell which allows a creature to become an object would stay in effect so that they can become a TRex. I cannot think of any off the top of my head, standard polymorph only converts creatures to creatures, and things like meld into stone don't actually make you a stone and even the illusion wizard's feature of one illusion object becomes real doesn't strictly speaking help as this+image of rock over your familiar just traps them in a rock (or shifts them out to one side of the rock)

Being a big enough rock

arguably given that object to creature requires up to the same size it likely works in reverse too that going from creature to object does not allow you to gain a size category but that's more my opinion rather than rules

qualifying as a companion

given that polymorph has a duration, it is not the creature's 'true' form so one might argue they are still eligable to be your familiar and entitled to the same benefits. On the other hand, their current form would certainly not be eligable to be a familiar and hence would not be entitled to the benefits of being a familiar.

In either case, assuming loyal treatment they should be friendly towards you

being a familiar

the same issues exist with two castings of true polymorph. Given that the find familiar spell has them choose a form when cast, it suggests they are a formless spirit before casting the spell but you cannot necessarily choose a new form for them when recalling them from their pocket dimension, they remain in the form they were previously in. As such, if the double polymorphing worked then yes they would come out of the plane in the form they were changed to, even a single polymorphing should last across pocket plane shifting though.

bottom line

barring another spell which allows polymorphing to an object, I don't see a way for this to work within the rules, there are however significantly easier ways to get similarly powerful allies.

Hope that helps! cheers,


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