I was able to complete all 25 waves with this with ~700-900 stats (I used a DPS barbarian during Combat Phase).
Hint 1: about 90% of all Ogres are going to be at this chokepoint, so this is where you will need to be for most of the Combat Phase.
Hint 2: These are just to support the spiders that will drop in. You will most likely have to repair this during the wave on the later waves
Make sure you are repairing your Strength Drain Aura, it is the first thing that will deplete during the wave.