A new “feature” in Alpha 17 7 Days to Die, is the zombie horde damage bonus addition. In short, when zombies “horde” up (ie, group up), they will each get an incremental damage bonus to their hits. This is definitely an interesting feature, and I take a look at testing this out, how it seems to work, how much it seems to be, and my thoughts around it.
The results seem to indicate each additional zombie has an extra 10 % PER each other zombie in the list. Ie, first deals 100 %. Second 110 %, third 120 %, fourth 130 % and so on. So you can imagine zombies grouping up 10 of them, with a base damage of 100 and suddenly doing up to 200 damage per hit. Together with the new zombie ai targeting structures/pillars, be ready to bring the house down!