Quote Originally Posted by PhoenixPhyre View Post
By the books, it does an additional (averaged) 0.833 DPR [(2d6[0] - 1d6 - 1)/3] compared to a regular zombie, with the rest being equal. I'm away from my data right now, but I doubt that that would push it over any boundaries. So not counting the stun effect, no change.
I went ahead and ran the DMG calculations. Which as you point out, is just recalculating the numbers for a standard zombie, because the DMG has nothing to account for status effects. 0.833 damage more doesn't shift the Offensive Challenge.

Defensive Challenge: 0

Offensive Challenge: 1/4

Overall Challenge: 1/8

I didn't learn much from this, other than that the DMG disagrees with the MM on what a zombie's CR should be (MM says 1/4).




If we want to make a number of assumptions, here's some back-of-the-napkin math that I'm going to put forward as a rough estimation of how much more effective the stun effect causes the Screamer to be.

We're going to say the Scream gets to use Scream once and that on average, two of the party will fail. That likely draws combat out from the DMG-assumed average of 3 rounds to 4, because of the lack of offense from the party for the round where two characters are stunned. The zombies you plan to have accompany the Screamer also have advantage to hit the stunned characters, so we'll say two attacks hit that wouldn't have. We're also going to say the extra round of combat causes two more hits to occur. At four damage apiece, that's sixteen extra damage over four rounds, or about four extra damage a round.

If we go with this math, the Screamer's Offensive Challenge bumps up to 1/2. Which leaves the CR basically unchanged from a MM zombie.



To my own surprise, I'm going to say that the Scream won't appreciably change the CR of the creature. I'd be a little more worried if your party was 1st level, but I don't think it'll make a difference if they're 4th level.