Decimating Flash of Force

Stretching out one hand and bracing it with your other you form a growing ball of raw charged arcane energy. You can concentrate this spell instead of casting it immediately, having disadvantage on concentration checks  to maintain the spell when doing so. When you cast this spell a 120ft 10ft wide beam of destructive force pulses out from your outstretched hand dealing 10d8 force damage to all creatures caught in the destructive wave.

1. On your first turn after starting concentration on this spell next the damage dice doubles for the spell.
2. On your second turn after starting concentration on this spell the damage maxes, requiring no damage roll.
3. On the third turn of concentrating on this spell any creature in the area of effect has disadvantage on the save

Each creature in the line must make a Dexterity saving throw. A creature takes 8d6 lightning damage on a failed save, or half as much damage on a successful one.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage increases by 2d8 for each slot level above 3rd.