Arcane Great Blade

The spell caster will gather an arcane aether to either their blade, staff, or casting focus, upon casting, you attack with a great sword forged from the arcane aether energies, dealing 2d20 + spell casting modifier + proficiency bonus, to all creatures within a 10 ft line

The spell can be charged further by waiting an additional turn (up to 2 turns) to add a further 1d20 to the damage. In total you can have 4d20 + spell casting Modifier + Proficiency bonus.
(With each increased charge level the blade grows an extra 5 ft for a maximum range of 20 ft)

This spell can be cast at higher levels as well, with each higher level it increases by 1d20, for each slot level above 1st level.

creatures must make a dex DC, on a failed save they will take the full damage of the attack and be pushed back 10 ft from the user and knocked prone, on a success they take half the total damage and are not pushed back or knocked prone.