Homebrew Monk Subclass: Way of the Mage-Keeper
Background
This subclass was adapted from what was originally a villain npc stat block, that of a powerful member of a high elf inquisition organization made to serve the interests of the dying elven empire and in particular, its church. Once the most influential religion in the world, recent global arcane upheavals, political tensions, and the surge of many smaller grassroots religious movements are threatening the very existence of the Flame of Purity and her temple. Openly opposing these more populist movements and the newly reestablished draconic congress is too risky, however, forcing the church and her defenders to move in the shadows and develop small but powerful strike teams of an attack dog mage and a handler monk to keep them on a leash.
This is just the lore in my current setting, though - you could easily adapt this lore to fit any suitably unethical shadow organization that would want to Mold wizards and sorcerers into tools of power.
LEVEL 3
You are now the sworn keeper of a mage in the service of the elven empire’s secret service. Through the surgical implantation of an arcane crystal, this mage is now bound to you. Any of your Mage-Keeper abilities used against your bound mage have advantage, and any saving throws they make against your abilities have disadvantage. This bond can only be ended via the death of your mage (or a painful, dangerous removal procedure, the methods of which are a closely guarded secret). You may spend a ki point to know where your mage is located within 1000ft of you for up to 10 minutes.
Arcane Knowledge:
At third level, you have studied the arcane arts and how they are wielded within the body. Gain proficiency with the Arcana skill if you do not have it already. It is now considered a Wisdom-based skill for you.
Arcane Disruption:
At third level, you have also begun to learn to use your ki to interfere with the flow of magic through others. On a hit, you may spend a ki point to end concentration on a spell or spell-like ability the target is maintaining.
LEVEL 6
Arcane Negation:
At sixth level, you have honed your abilities enough to stop a spell in its tracks. If you are within 5 feet of a creature casting a spell, you may use your reaction to spend at least one ki point (up to 3) to try to counter it. Make a Wisdom (Arcana) check, DC equal to 11 + the spell’s level - the number of ki points spent. If you succeed, the spell is countered. You may also use this ability to spend an action to try to dispel an ongoing magical spell or effect within 5 feet of you, with the same DC.
Arcane Exchange:
Also at sixth level, your connection with your bonded mage grows stronger. As a bonus action, you may touch your bonded mage and restore their missing spell slots, spending one ki point for each spell level restored. You cannot restore slots above the level that your caster can already regain on a long rest. You can also remove spell slots from your bonded caster. They can either give them up willingly, or you can touch them and force a constitution saving throw, DC equal to 10 + your proficiency + your wisdom modifier - the level of the spell taken. You gain a number of ki points equal to the level of spell removed from the caster.
LEVEL 11
Arcane Resistance:
At eleventh level, you have advantage on all saving throws against spells being cast by a creature you can see.
Arcane Deflection:
Also at eleventh level, you gain the ability to reduce magical damage. If you are damaged by a targeted spell cast by an opponent you can see using fire, cold, thunder, lightning, necrotic, force, or radiant damage, you may spend your reaction to roll 1d10 + your monk level to reduce the damage by that amount. If the damage is reduced to zero or below, you can spend 1 ki point to make a ranged attack with a range of 20/60 using the spell energy you just caught, as part of the same reaction. You make this attack with proficiency, regardless of your weapon proficiencies, and the damage is equal to your monk weapon die + your wisdom modifier, and of the same type of the original spell.
LEVEL 17
Arcane Redirection:
Once per turn, if you or a creature within melee range of you is the target of a spell, make a Wisdom (Arcana) check, DC equal to 10 + the level of the spell. If you succeed, you may redirect the target of the spell back at the caster or at another creature within range as though you cast the spell yourself.
Arcane Suppression:
Once per long rest, you may spend 4 ki points as a bonus action and activate a Null Magic Zone around yourself, extending into your threatened space in every direction and lasting for up to one minute. Anyone within that space cannot cast spells of any kind, and any concentration spell a creature is holding automatically ends. If you or anything in range of you are the target of any spell, it automatically fails to take effect. Any magical items you or anyone within range are carrying have their abilities temporarily suppressed and rendered useless until the effect ends or the items are removed from range. While you have this Zone active, you may choose, on a hit, to make an Arcana check to identify any possible attunements a creature you strike may have to magical items. You may then use your reaction to spend two ki points to end that attunement.
