At which stage should I go for Tesla(present I am in Brazil level)

Badsda

Is it worth spending money for Tesla or Heavy Gun and if worth which one is worth buying and at which level currently I am in Brazil level.

Zvonko

If you have to spend real money for it - no! If I were you, I'll wait until Vigore III level. With that Tesla/Heavy gun you can play all the levels before it, have a tons of diamonds and progres in big leaps forward without a cheating. Don't forget to upgrade your tier before jour guns. That way you'll be at level 300+, get lot of gold so you can buy another Tesla/Heavy and finally enjoy in the game!