Martial Archetype: Martial Mage
Though the strength of martial mages lies in their mastery of weapons, they are also able to imbue their strikes with magic for more versatile attacks. Because of their limited arcane energy, they are unable to cast spells, but these fighters can enhance their ability in the battlefield with magically charged hits.
Weapon Bond
At 3rd level, you learn a ritual that creates a magical bond between yourself and one weapon. You perform the ritual over the course of 1 hour, which can be done during a short rest. The weapon must be within your reach throughout the ritual, at the conclusion of which you touch the weapon and forge the bond.
Once you have bonded a weapon to yourself, you can't be disarmed of that weapon unless you are incapacitated. If it is on the same plane of existence, you can summon that weapon as a bonus action on your turn, causing it to teleport instantly to your hand. The weapon is considered magical for the purpose of overcoming resistances.
You can have up to two bonded weapons, but can summon only one at a time with your bonus action. If you attempt to bond with a third weapon, you must break the bond with one of the other two.
Imbuements
When you choose this archetype at 3rd level, you learn to imbue your weapon attacks with arcane energy to damage or disable your opponents.
Praecantations. You learn two praecantations of your choice, which are detailed under “Praecantations” below. Many maneuvers enhance an attack in some way. Each use of a praecantation must be declared before the attack roll is made. You can use only one praecantation per attack.
You learn an additional praecantation of your choice at 7th, 10th, 15th, and 18th level. Each time you learn a new praecantation, you can also replace one praecantation you know with a different one.
Imbues. You gain a number of imbues equal to your Charisma modifier (minimum of 1). You regain 1 expended imbue each time you roll a 20 on the d20 roll for an attack with your bonded weapon, or deal a killing blow with a bonded weapon to a creature of significant threat (DM’s discretion). You regain all expended imbues after a short or long rest.
Saving Throws. Some of your praecantations require your targets to make a saving throw to resist the praecantation's effects. The saving throw DC is calculated as follows:
Praecantation save DC = 8 + your proficiency bonus + your Charisma modifier
Maddened Mage
Arcane energy swirls your weapon, strengthening and diversifying your strikes. When you reach 7th level, once per turn, you can add 1d4 of any of the following damage types to an attack made with your bonded weapon: acid, cold, fire, lightning, or thunder.
At 15th level, it increases to a 1d8.
Improved Praecantations
Upon reaching 10th level, you can use up to two praecantations per turn.
Swift Strike
Starting at 15th level, you become one with your blade and can wield it deftly and quickly. You gain one of the following features of your choice.
Betrayer’s Blade. When a hostile creature misses you with a melee attack, you can use your reaction to force that creature to repeat the same attack against another creature (other than itself) of your choice.
Fidelity’s Fury. When a hostile creature within your melee range hits an allied creature, you can your reaction to gain an attack on the hostile creature.
Vengeful Rebuke. When a creature hits your with a melee attack, you can use your reaction to strike back at them.
Improved Critical
At 18th level, your bonded weapon attacks score a critical hit on a roll of 19-20, and you regain an imbue on a roll of 19 or 20 on a d20 attack roll.
Vanishing Trick
Upon reaching 18th level, once per day, you can use the vanishing trick. You strike with your bonded weapon at your opponent from up to 30 feet away then vanish to strike like the wind. Choose up to five creatures you can see within range. Make a melee weapon attack against each target. On a hit, a target takes 6d10 damage from your bonded weapon.
You can then teleport to an unoccupied space you can see within 5 feet of one of the targets you hit or missed.
Praecantations
Praecantations that can be learned are listed below.
Beacon. You expend one imbue that causes your blade to glow a bright light in a 15 foot radius and dim light in a 50 foot radius. Any allied creatures who can see this light have 5 temporary hit points as long as the light can be seen. This lasts up to 8 hours or until dispelled.
Blade Boost. When you make a bonded weapon attack against a creature, you can expend one or more imbues to increase the size and volatility of your weapon. If the attack hits, you can roll one additional weapon damage die per imbue spent when determining the damage.
Echo Attack. When you make a bonded weapon attack against a creature, you can expend imbue to attempt to strike through multiple opponents. This praecantation causes spectral copies to burst out of your weapon. On a hit, the creature suffers normal damage and you make an attack roll with disadvantage against every creature in a line directly after the target within your first range increment.
Exploit Weakness. When you make a bonded weapon attack against a creature, you can expend 1 imbue to gain a brief insight into your target's defenses. Your bonded weapon exploits your opponent's weakness and you have advantage on the attack roll.
Forceful Strike. When you make a bonded weapon attack against a creature, you can expend one imbue to attempt to trip them up and force them back. Your weapon's mass increases briefly and on a hit, the creature suffers normal damage and must succeed on a Strength saving throw or be pushed 15 feet away from you.
Parasitic Punch. You expend one imbue to give your bond weapon the power to siphon your opponent's life force. On a hit, you regain hit points equal to half of the damage you dealt.
Strength Sap. When you make a bonded weapon attack against a creature, you can expend one imbue to attempt to weaken your opponent temporarily. You imbue your weapon with the ability to siphon your opponent's strength. On a hit, the creature suffers normal damage and must make a Constitution saving throw or suffer disadvantage on attacks until the end of their next turn.
Unstable. When you make a bonded weapon attack against a creature, you can expend one imbue to attempt to topple a moving target. Your weapon temporarily distorts the opponent's sense of balance. On a hit, the creature suffers normal damage and must make a Strength saving throw or be knocked prone.
Wound Warp. When you make a bonded weapon attack against a creature, you can expend 1 imbue to imbue your weapon with a specific type of arcane energy. On a hit, you choose what type of damage the creature takes: acid, bludgeoning, cold, fire, force, lightning, necrotic, piercing, poison, psychic, radiant, slashing, or thunder.