Low-Orbit Drop is a generally forbidden spell known only to very few ritual war evokers, and traditionally used in sieges due to its extensive casting time and horrifyingly destructive effect. The use, especially against civilians will likely lead to the caster being hunted by magic organisations, as well as possibly shunned by most polities.

The caster reaches out far into space, nudging the orbit of a small wandering star into a collision course with the target point.  After the duration of the spell casting, no sign of the effect is visible for 1d100 hours. After this length of time, a flaming trail appears in the sky, followed 20 minutes left by the impact of a flaming object at the target point. Objects and creatures in a 500 foot circle area must succeed on a dexterity saving throw or receive 30d6 fire damage and 30d6 thunder damage. The fire damage halves every 200 feet outside the original radius, and the thunder damage halves every 400 feet. When one of these effects does less than 1d6 damage, it no longer does any damage. 

Creatures inside structures or behind heavy cover take half damage. However, buildings are collapsed in a 600 foot radius of the impact. Creatures inside a collapsing building must roll a DC 20 Dexterity saving throw or take 6d6 bludgeoning damage and become prone. While prone, the creature cannot move unless the rubble is removed. On a successful save the creature takes 3d6 bludgeoning damage and does not become prone. A creature can use its action to make a DC20 Athletics check to remove one creature from a collapsed building.

Flammable objects and plants in a 1400 foot radius of the impact combust.

If the spell impacts water, coastal areas for 1d4*10km around the impact site suffer the effects of the Tsunami spell.

*for ease of use, most creatures can be assumed dead if they would not survive the average damage