I'm trying to better understand the Werewolf so that I can design my own varieties of homebrew Werewolves for my campaign. I started by adding together all the stats of the Monster Manual's Werewolf and treating it as if I were building the monster by the DMG's rules.
I used the Hybrid form as the default, since it is the strongest of the three forms in combat. I calculated the ability scores, AC, and base damage for its attacks. I even doubled its effective HP for the damage immunities it has, as per DMG 277 which indicates that a CR 3 monster with 1-3 immunities should multiply its effective HP by x2.
I discounted shapechanger and its other abilities/effects because they didn't seem to have any impact on challenge. By the time I was done, I calculated the variables and ended up with a CR 1 Monster. (Even though I went with the best-case stats across the board)
A Werewolf is supposed to be a CR 3 Monster. So where are those other two points coming from? The only thing I can think of is its Bite effect (save against lycanthropy) but I was under the impression that saves against non-damage didn't affect CR. What have I not accounted for that is worth two whole points of Challenge Rating? If it is to account for balance, should I account for this 2CR discrepancy in my own homebrew werewolves.