I thought the canonical answer was that a CR10 monster would provide a reasonable challenge to a party of 4 10th-level characters.
They themselves show examples where CR doesn't really work - for example, the Imp I believe is CR2 or 3 and can come in swarms. Each Imp can fire off 3 magic missiles at will, which could easily kill a 2nd or 3rd level Wizard (or even Rogue) dead... let alone a swarm of them.
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Date: 2007-11-19 03:20 pm (UTC)They themselves show examples where CR doesn't really work - for example, the Imp I believe is CR2 or 3 and can come in swarms. Each Imp can fire off 3 magic missiles at will, which could easily kill a 2nd or 3rd level Wizard (or even Rogue) dead... let alone a swarm of them.