[RPG] Are there higher CRs possible than the Tarrasque’s CR 30


We were discussing with a DM friend of mine about the challenge ratings in D&D 5, and I affirmed the highest known to this day in the official content is the Tarrasque, with a CR of 30.

He then said that this wasn't true, and that there was some kind of "mythical" mode that could be enabled and which would include/allow even more deadly creatures. The problem is, he could not remember where he read that.

Did I miss something in the tryptic? Is it possible, RAW, to create monsters with a higher CR than 30?

Best Answer

Firstly, there are no official (as in, published by WotC) monsters with a CR higher than 30.

The rules for creating monsters are on page 273 of the DMG. While there is no explicit statement that monsters are limited to CR 30, all of the tables and rules for monster creation that depend on CR only go up to 30.

The DM can (as always) do whatever they want, but to create a monster with a higher CR than 30, they'll have to invent a lot of numbers. For example, the experience points for defeating it.

On the other hand, the hardest part about making a monster of CR >30 would actually be assigning it a CR. The majority of the monster creation guidelines are about assigning a CR to the monster.

To cut a long story short, whatever your friend is thinking of is either homebrew, 3rd party material, or something from a previous edition.