Up to 1 minute
You draw power from the earth and a pillar of unstable arcane energy erupts from it eager to lash out of it's confines. When a cantrip or spell below 4th level is cast within range, the pillar follows the source of the spell and deals 2d6 lightning damage to the creature that cast it. Once the pillar attacks, it crumbles to dust.
If this spell is cast using a 5th level slot, the pillar will not crumble to dust after the first attack, but will attack again when another spell is cast (of 4th level or below). At 11th level, the pillar can make 3 separate attacks. And at 17th level, 4 attacks.
a piece of static charged fabric
Columna Incendio Stabilis