I am currently experimenting with a Corrosion + Aoe dmg build .. But i always end up with around 30+ lives when i hit the Ronald stage which is not enough to survive long ? i play Normal btw >< .
I'll try to describe as accurately as possible ..
At the start, i select water and then followed by darkness to get the Poison>Pollution>Pestilence towers for some AOE dmg. I built some focused/refined water towers around the Pollution towers for combined Aoe dmg . Some Fire towers too after getting the fire element later in the game.
The Single dmg towers i built was Focused/refined darkness towers + some Magic>Sorcery>Wizardry towers clumped together .
I placed those Aoe Dmg towers at the middle of the path and Single dmg towers at the start of the path .
Corrosion towers were placed nearer to the AOE dmg towers . However, the effects of the armour reduction still aids the Single DMg towers due to the range of Darkness towers. EleTD4.2E.w3g