Strategy for WORLD 2 (W2).
I'm not sure, if my strategy for W2 is comparable to previous... But it works. So here is my way how to pass through second world. If you really need it, try this process:
1. there is no crossroad on the W2 map, so it's necessary to concentrate on another suitable place - one of them is near the start, there you can build all needed mushrooms (12 again)
2. 8 of them will be upgraded to wealth towers later, 2 to splash slow type of mushroom and 2 to splash poison, start with upgrading of mushrooms in upper line (at least 2 of them to level 4 or 5), then apply elements combination to make 1 splash poison and 1 splash slow tower from first two mushrooms in the line (let them on level 3) and finally finnish first half by using elements for first 4 wealth towers
3. similary go on with bottom part of formation
4. upgrade all remaining wealth towers to level 5 gradually, then continue with upgrading splash poison towers to level 5 and splash slow towers to level 4 at the conclusion
That's all. Quite simple, unfailing, with no life lost usually... Try it!
Next lesson - WORLD 3 (W3). But I just don't know when...