Boom Shroom

1 Poisonous flammable mushroom appears in a location you choose within range. The mushroom produces a cloud of poisonous spores of up to ten 10-foot cubes from the shrooms. Each creature that enters the mushroom’s area of effect for the first time or starts their turn in the area must make a Constitution saving throw on a success they take half damage on a fail they take 4d6 poison damage. The mushroom last for one minute or until the concentration is lost. The caster can choose spend an action to detonate any number of mushrooms destroying them but causing a fiery explosion.  Each creature in the area must make a Dexterity saving throw. It takes 4d6  fire damage on a failed save, or half as much damage on a successful one.

The fire damages objects in the area and ignites flammable objects that aren't being worn or carried. If you choose, plant life in the area is unaffected by this spell. For every level above 3rd that you cast this spell you can add another mushroom.