Thiriax's Nails

The caster animates the 4 steel nails in their hand which swell in size and hunt down any number of targets inside of the 1 kilometer area. The nails have a fly speed of 60 ft, and cannot dash. The nails radiate heat, and when a nail strikes a designated target, it halves their base speed for 18 seconds and does 6d6 fire damage + 2d4 piercing damage. This speed reduction cannot stack. The nail, after hitting a target, calls out to the other animated nails, which also seek the target. If another target on the list is detected by a nail, that nail will hunt that target instead of responding to the calls of other nails.

For every turn that a nail remains in a target, they take 3d6 more fire damage until they take an action to remove or restrain the nail. A casting of dispel magic at a higher level knocks the nail out of the sky, which returns to flight in 30 seconds, and an antimagic field cast at a higher level than the nails will render it a regular nail until the spell is cast again, reanimating it or the antimagic field is dispelled. If dispel magic or counterspell is cast at a lower level, the nail is knocked down for six seconds. Once the hour elapses or concentration is broken, the nails return to the caster, ignoring any targets on the list and report how many targets were killed, how many targets remain, and their last known location. If the nails cannot see one of their targets for 12 consecutive seconds, they will search other areas.