Just need a few suggestions, I want to add more cards such as jokulhaups, obliterate and worldslayer but nothing that is straight-up MLD. In short, similar spells/permanents which seal the game if they are allowed to resolve.
There's a pretty solid Zurgo list here, posted by DementedKirby, who is an active forum member. If you're looking for Zurgo-specific questions, this is probably a great place to start. List does look a bit dated.
Agreed, a decklist would help. I presume from your post that you want boardwipes that wipe more than just creatures, but don't want pure land destruction spells like Armageddon. Ideally it looks like you want spells that nuke lands incidentally, but that don't remove Zurgo himself.
The decklist can be found here, note however that it is currently being revised with the idea of adding more cards providing double strike to ensure a faster game. Some cards may seem suboptimal but I am tinkering with what I own at the moment, so feel free to mention obvious cards to add that I might have missed, if you can.
My playgroup is casual but has some pretty good decks, but nothing with infinite combos or turn 4 wins. My goal with Zurgo (helmsmasher, you got that right) is to make games shorter, especially when it is getting late and I want to sneak in a last game.