Quote Originally Posted by PhoenixPhyre View Post
An aoe, friendly-fire-free (if they're running with zombies), no immunity stun that deals damage, even with a low DC, is a hefty effect. And one that CR (in particular) is not well equipped to model/correct for.

Anyone with +2 CON and no save proficiency has a 45% chance of losing their next turn and getting smacked by all the other zombies. In a 3 round fight, that means that there's the following breakdown:

Rounds stunned | Chance
0 | 16.6%
1 | 40.1%
2 | 33.4%
3 | 9.1%

So there's a 77% chance you will spend either 1/3 or 2/3 of the fight out of combat. That's brutal. And not so fun. Hard control (complete action denial) is rarely very fun at all for the players. You're basically saying "don't play a melee character" here.

Personally, I'd downgrade it to something like a piece of what slow does (reduced movement, action OR bonus action) or add in a "if you succeed, you're immune for X time" clause.
Hmm, appreciate the comments but I'm not convinced things are as dire as you believe. The ability is akin to a sound burst spell, only it has to be centered on the Screamer, it deals less damage, has a wider effect radius but has a lower DC and can be used seldomly. Chances are it will only go off once in a fight being on an AC 8 22 HP chassis and requiring a recharge roll. It is very much meant to keep characters away but I don't think that encouraging a tactic for an encounter type necessarily means it isn't worthwhile to play melee in the campaign. This is in a modern campaign as well, so one can be expecting there to be high base damage firearms available to them even if you're primarily a melee character.

What CR would you give it in its current state?