There are two games I know that is just like this. Monster Galaxy and Miscrits. So if I will rate the 3 of them, here is the result. Monster Galaxy - 7 Miscrits - 9.5 Terra Monsters - 9.8.
new elemental weapons my opinion: Flaming Fury (shoots short range flames that can melt ice and burn players, 20% chance of critical strike),Freezing Ice ( freezes enemies and damages) ,Nature's Wrath ( shoot's leaves that can slice metal)
Haven't thought about that. But I planning to add special ball/balls which you get after completing missions.