You conjure a black monolith in a space that you can see at a point of your choosing, where a portal of black light and violet lightning opens its maw and the monolith slowly descends from. The monolith is made of an indescribable, indestructible material and emits a low, menacing hum. It is 5 feet in depth, 20 feet wide, and 45 feet tall.   It emits an intensely strong gravitic field in a 45 foot radial sphere around the center of its base which can repel or attract any metal objects. The gravitic field slightly distorts light around its perimeter and is nearly invisible.   When you first summon this monolith, you may choose whether it repels or attracts metal objects and projectiles. On each of your following turns, while you are concentrating, you may change the polarity or turn the field on by using your Action. You may, at will, turn the field off as a Free Action. When you switch the polarity, you must wait until after your next turn before changing it again.   You must maintain concentration to keep the monolith summoned. If concentration is broken or it is dismissed, the monolith slowly sinks into a roiling torrent of black light, crackling with lightning, and all traces of its existence vanish, leaving whatever was stuck to its surface arranged around its rectangular edges.   Any target wearing or carrying metal that enters the field emitted by the monolith, if they wish to resist its effects, must make a Strength saving throw against your Spellcasting DC when they first enter the field or start their turn in the field. Targets wearing heavy armor or carrying heavy weapons have disadvantage on their saving throws. If the target fails their throw while carrying a metal object, the object is pulled out of their hands.   If the metal object they are carrying is pulled out of their hands, then it is instantaneously pulled to the surface of the monolith with a loud clang. Any creatures in the path of the object or weapon must make a Dexterity saving throw against your Spellcasting DC, or take the weapon's damage.   If they fail while wearing metal, they are pulled towards the monolith at an increasing rate of movement speed per turn, starting at 10 feet and doubling every turn after. While being pulled towards the monolith, movement away from the monolith is halved. The inverse is true when the Monolith is set to repel.   To escape the monolith's field, captured targets can choose to remove their armor, drop their weapons, or remove any metal from their inventory.   If you set the monolith to repel objects, any targets wearing metal objects can be launched up to 50 + 10x your Spellcasting Modifier in feet if they have been pulled to the center, and are treated as falling when launched.   Any metal projectiles are instantaneously captured by the monolith when it is set to attract objects. While the monolith is set to repel objects, it will reflect the object in a straight line back to from where the projectile was launched. The target that launched the metal projectile must make a Dexterity saving throw against your Spellcasting DC or take the weapon's rolled damage.   Any projectiles or objects captured by the Monolith while it is attracting can be repelled in a straight line away from the monolith, up to a maximum of 500 feet away, colliding with any objects in its path. Any targets caught in the paths of the repelled projectiles or weapons must make a Dexterity Saving Throw against your Spellcasting DC or take damage based on whether it's a weapon, projectile, or loose metal object. Successful saves take no damage. The objects themselves take the same amount of bludgeoning damage as the targets they hit.  

Weapons and Projectiles: Damage rolled plus the caster's Spellcasting Modifier in Bludgeoning Damage

Tiny Metal Object: A number of D4's equal to the caster's Spellcasting Modifier in Bludgeoning Damage

Small Metal Object: A number of D6's equal to the caster's Spellcasting Modifier in Bludgeoning Damage

Medium Metal Object: A number of D8's equal to the caster's Spellcasting Modifier in Bludgeoning Damage

Large Metal Object: A number of D10's equal to double the caster's Spellcasting Modifier in Bludgeoning Damage

Huge Metal Object: A number of D12's equal to double the caster's Spellcasting Modifier in Bludgeoning Damage