Hey bud, i copied and pasted your deck list by finding the URL address for it in your deck list. I hope this helps.
Now to your deck suggestions; 1. Add more cards that say your opponents can not gain life.
Sulfuric vortex and such cards put more pressure on your opponents so that they really.....wait for it......"feel the burn"
2. Next focus on more hand hate tactics. If you are making people draw cards faster then they will be able to get to answers for what they need faster.
Skullknocker ogre and
collective defiance are good add ins that go with your deck theme. Also
dragon mage, i believe that if you give him and the ogre
fireshrieker then their effects should trigger twice per attack (cause the double strike means they hit two times per attack declaration.
3. I know you want the deck to focus on Zuroth, but if you consider adding black to the deck then you can have
Rakdos, the Showstopper as the commander. You can have a one sided board wipe at the ready at all times because your deck with be DEVIL tribal and his effect won't touch your board. Also this lets you add
liliana's caress,
megrim,
fell specter, and
raiders' wake which will burn everyone for the cards they discard as well. All just suggestions but i hope they help.