1. Golden Orcs and Sharken are a major problem in these areas early on, do NOT let they get through or else you will run out of units that you need for later
2. You can substatute the Striker Towers for Proximity mines, as the top paths will be soley handeled by auras, if you have smaller aura go for Proximity and if you get wrecked by ogers then go for Strikers
3. Last thing you need to upgrade, not many ogers come this way
Just spam upgrade your things and you should be fine! I would recommend waiting for last wave to join in alts with an emulator if you just want loot.