Tri-Beam

You create a devastating wave of energy that surpasses
normal spells at the cost of your vitality. You gain two levels
of exhaustion, or only one if you already have at least one
level Additionally, you take an amount of necrotic damage
equal to twice this spell's level.
Every creature within a 20-foot cube originating from a
point you choose within range must make a Dexterity saving
throw. On a failed save, they take 5d10 + 20 force damage and
are pushed 20 feet away from you. A pushed creature that
impacts a solid surface is stunned until the end of your next
turn. On a success, they take half as much damage, are not
pushed, and can instantly use their reaction to move up to
their speed to the nearest unoccupied space outside of the
spell's area.
Any terrain, structures, or non-magical objects that aren't
being worn or carried within the spell's area are reduced to
dust by this spell If the terrain below a creature is
destroyed, they fall.
At Higher Levels. When you cast this spell using a spell slot
of 6th level or higher, the damage increases by 1d10 for each
slot level above 5th.