The thing is I started to use Earth elementals, along with water and fire ones, but it was useless, and I aslo didn't had enought mana to make a V, even tried to do Fire/Water bomb but they killed my water before I could create it, please help.
what? how do you not have enough mana? did you mean gold?
but as rain stated, Yes. Trees will allow for you to apply constant pressure without committing with a hefty amount of resources to do so after their creation. They will be your primary stage presence and push option. Tower Spawn will be a must to further your pushes without committing to combining into an actual charrog every time you have to run back and forth across the stage. Infernoes will be your close game if they continue to produce archers heavily without thinking about an actual composition and controlling that composition thusly. These units will quickly and severely damage all units within its two area of effect attacks, however, the secondary spell must be upgraded to be as effective as possible. (Think of it as an area Suppression unit) I would highly recommend you attempt to create 3 trees before teching directly into V afterward with the corresponding upgrades as it will be very effective around the time it takes to spawn those 3 trees. (Use its tertiary ability to control tank units your opponent has, softer priority targets like merics/shadowrath, and Primary targets like magikill and other heavy casters)
