you need
Plague Belcher. You have close to my original deck idea. I use
Metallic Mimic to get my zombies coming into play with +1/+1 counters. Then Lord of Accursed adds another +1/+1. Then as they are coming into play with
Wayward Servant you deal 1 and gain 1. With
Plague Belcher in play, when you dusk, All your dying zombies will do another point of damage.