Cosmic Djinn (Deep Space Djinn)

The Cosmic Djinn draws from the depths of space to bring forth fragments of the nearest asteroid comet or meteor.  Fragments envisioned in the mind of the caster narrow and focal to the point flashing through the field of battle.  Casting this spell takes 18 seconds(3 rounds).  A line 100 feet long and 10 feet wide blasts out from the depths of space in a direction you choose. Each creature in the line must make a Dexterity saving throw.  On fail enemies within take 10d6 bludgeoning damage.  Half on success.  The line ignores cover and continues in unoccupied space to max distance.  The area becomes difficult terrain for the duration and lasts for an hour. When a creature starts, moves into or within the area, it takes 4d4 radiant damage for every 5 feet it travels.   When casting, Hellish Rebuke is cast once per round if needed until Cosmic Djinn spell is cast

At Higher Levels. When you cast this spell using a spell slot of 7th level or higher, the damage increases by 1d6 for each slot level above 6th..