I am on day 163 and still going (very fast and long waves 7. Hunter, Sniper, Ranger, Ranger. Cross bow, Cross bow, Magnetic, Magnetic. Make sure you have weapon with lots of Mod space. Leech, Fire Rate, Damage, Impact most important. Some Cross Bows have 5 mod spaces. Add Anti Armor. Utilize the Save game, if you have lots of AP (active skill) the shop re-shuffles new items to buy.