Energy Mine

Upon activation, you leave a ball of energy 5 feet in front of you. If there is a creature within 5 feet of the ball, it immediately detonates for 2d8 force damage for any creature in that 5-foot range; the caster is immune to its damage. Once summoned it remains stationary and can not be unsummoned; the only way to get rid of it is by a creature being within 5 feet or a projectile making direct contact with the mine. If the projectile is magical or elemental in nature, it is theorized that the detonation takes on that magical or elemental property, and still needs field testing. 

While this spell can not be upcast, there are upgrades to the spell depending on the player's level, regardless of multiclassing. Below are the upgrades that occur at the different levels:

1. At player level 5, the spell allows for two mines to be dropped in one use of the spell.
2. At player level 8, the initial launch and detonation radius is doubled to 10 feet. 
3. At player level 11, each mine now has two detonating blasts; each blast on each mine still does the same damage and each mine only disappears after the second detonation.
4. At player level 14, damage from all detonations causes a knockback effect pushing each creature back 5 feet, and each creature must make a dexterity saving throw against a DC 14. On a failed save, the creature is knocked prone. 
5. At player level 17, all damage from the mines is doubled; roll the 2d8 and double the final value.