Voltile Artillery

When you cast this spell, 4 glowing spikes of fiery energy coalesce, floating around you. For the duration, 1 spike is summoned at the start of your turn on every round. As a bonus action on your turn, you may release as many of these spikes as you want, targeting one enemy within range. Each spike deals 1d4+2 fire damage. When a hostile creature moves within 5ft of you or attacks you, they take damage equal to the number of spikes around you. If you lose concentration on this spell, the remaining spikes explode, and each creature within 15ft including you must make a constitution saving throw against your spell save DC. On a failed save, each creature hit takes 2d4+2 fire damage per remaining spike, half as much damage on a successful one.

At Higher Levels. When you cast this spell using a spell slot of 5th level or higher, 2 additional spikes are summoned to start, and 1 additional spike is summoned each round for each slot level above 4th.