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