Elemental Streak

You stamp your foot or press your hand to the ground and a streak of energy shoots out from your hand/foot. It moves towards an enemy within range, glowing under the earth, and does 1d6+4 choice force damage, the targets being thrown back 10ft and landing prone. (This is as an earth element based spell. An additional 1d6 can be added for lightning, thunder, ice or fire damage.)

With every spell level, you can add another target, it does an extra 1d6 force damage (but no additional elemental damage) and the targets are thrown back an extra 10ft.