Lawmage

You force penalties on those who break rules only you know.

True Savant

Starting at 2nd level, the gold and time you must spend to copy any abjuration, divination, or enchantment spell into your spellbook is halved.

Absorb

Starting at 2nd level, whenever you successfully cast a non-damage dealing spell you may gain HP equal to the spells level. You may use this ability a number of times equal to your Intelligence modifier (min 1). You regain expended uses when you finish a long rest.

Overrule

Starting at 6th level, you may sacrifice spells as a reaction to interrupt a creature in the process of using an ability, but not spellcasting. If the creature has a CR equal or lower to twice the sacrificed spells level, its ability fails and has no effect. You may sacrifice multiple spells when you use this ability. If an action gives multiple actions multiple the spells needed by the amount of actions given. You may use this ability a number of times equal to your Intelligence modifier (min 1). You regain expended uses when you finish a long rest.

Detain

Starting at 10th level, as an action you may choose a creature you can see within 60 feet and give them the Stunned condition until the start of your next turn and any creature who targets the creature with an attack or a harmful spell must choose a new target or lose the attack or spell. You may use this ability a number of times equal to your Intelligence modifier (min 1). You regain expended uses when you finish a long rest.

Detention

Starting at 14th level, when you cast Banishment, instead of sending the target to another plane you may create a physical sphere in any square the creature was occupying and trap them inside it. Duration changes to Instantaneous. The creature gains advantage on their saving throw.

The sphere expands to a size just large enough to contain the creature. While encased, the creature doesn't need to breathe, eat, or drink, and it doesn't age. Nothing can pass through the sphere, nor can any creature teleport or use planar travel to enter or exit the sphere.

The sphere is a construct of medium size, AC equal to 10 + your spellcasting modifier, HP equal three times your level, and resistance to all damage, weight 100 lbs. You can willingly destroy a sphere as long as you are within 60 feet of it as if you were ending concentration on a spell.

As a bonus action, you can move the sphere and its contents up to 30 feet in any direction. A successful casting of the Dispel Magic spell on the sphere (DC 15) destroys it. The sphere otherwise remains intact until you spend an action to end the effect or you die. You can maintain a number of active spheres equal to your Intelligence modifier (min 1). If you create a sphere when you already have your max amount active, the first sphere created disappears, freeing the creature inside.

Note: I found the Advanced Detention Drone in the BMT after I created this ability and it has a few additions that I think help the ability. I have italicized the stuff I took for the A.D.D., and struck out stuff it overrode to make it clear.