Bangalore Ultimate- Rolling Thunder

The caster creates a 15-by-15 feet cube within 60 feet of themselves. Everyone within that space must make a Dexterity saving throw. On a failed save, the creatures take 2d10 explosive damage plus the caster's spellcasting modifier, and their movement speed is halved until the end of the recipient' next turn. On a successful save,  the creature takes half damage and their movement speed remains normal.

At higher levels: At 5th level, the damage increases to 4d10. At 11th level, it increases to 6d10 and the recipients' movement speed is halved for 4 rounds . At 15th level, it becomes 6d10, and at 18th level, it becomes 8d10, and the recipeients' movement speed is halved for 6 rounds.