in beast, they are called "tremble" and "rain of inferno." Tremble is a reusable cast item with a cooldown and mana cost, which does a medium amount of damage. Rain of inferno does a huge amount of damage to a large radius, but is one use and costs the vamp 75 gold. I agree that these could be too powerful in a game where humans rely on towers for defense (you don't have to have towers in beast until later in the game). To attenuate their effects, you could lengthen the cooldown for tremble, make rain of inferno cost more, make both do less damage or shorten their area of effect. I would encourage you to consider these, but to pick just 1 or 2, not to do all of them... then these items would be worthless to the vamp.