Quote Originally Posted by sandmote View Post
5e d&d has rules for this in the Dungeon Master's Guide, but even then the edges between different CRs are fuzzy. Status effects in particular are a pain to quantify.

If you're throwing only three or fewer zombies at the party, you could maybe justify CR 1/2, but if there's a bunch of them CR 1 seems more accurate to reflect party members getting regularly stunned.

Although for playability I would maybe change Scream from "(Recharge 5-6)" to "(Recharge 6)," just to reduce the odds of stunlocking the party to death.
This particular zombie was designed to be accompanied by other regular zombies. That's kind of the intention, one screamer and a slew of regular Zeds due to their rarity.