I was discussing the spell with my DM relating to this question Can a Wizard polymorph low-level PCs into over-powered beasts? about the polymorph spell.
According to Polymorph's description,
The new form can be any beast whose challenge rating is equal to or less than the target’s (or the target’s level, if it doesn't have a challenge rating).
I was excited about the idea to turn one of my fellow group members into a giant ape or T-rex, but my DM told me that anyway with our current level (lvl 9) I would only be able to turn them into a CR 4 monster.
He bases his judgment on this part:
The new form can be any beast whose challenge rating is equal to or less than the target’s
From my understanding, PC's don't have a CR - CR seems to have been invented to adapt monsters' levels to players' levels (originally in D&D 3e). In other case, we could have just put experience levels to monsters instead of creating an alternate ranking system. And why does the spell specify:
(or the target’s level, if it doesn't have a challenge rating).
I'm still relatively new in D&D 5e world so I'm maybe wrong. I understand that at the end of the day the DM's word is law and I got no problem with that. But I was wondering if there was any precision points in the rules that I could show him if it's just a problem of interpretation?
I think that my DM isn’t making a house rule on purpose and is just misunderstanding the rules. I think he used a "conversion array" that he found on google: something like a level X creature is a normal threat for 4 level X PCs. Right now he tells me that he is right and the spell is just badly written.
So the question is does a PC fall under the
The new form can be any beast whose challenge rating is equal to or less than the target’s
part of the spell's rule or under the
(or the target’s level, if it doesn't have a challenge rating).
part of the spell's rule? Please justify.