1. EV walls are temporary for first wave, build Minion walls 2nd (and 3rd wave if not enough time)
1.5. Don't build auras too close, you don't want them killing enemies up top.
2. At least one character needs to stand up top to agro them. Rest can too, or be dead or use a summoner in phase shift so they don't agro. Use a fairy, don't kill anything with a bow on their heads. (So no DPS pets)
2.5. if you don't agro top the map will just take a LONG time.
3. you can place a buff beam mid with just a heal aura on it to help you survive if needed.