Chainlinker

You gain the ability to modify weapons with chains and use chains to perform certain feats, ropes can also be used instead of chains. This gives you a longer range to attack with your weapons, potentially remaining outside the melee range of your target. The amount of damage you deal, the reach you have on your chain and the number of creatures you can target increases as you level up. You use your strength modifier to attack even if you are using finesse weapons with your chain.

You cannot use weapons that have the heavy or reach properties with your chains and versatile weapons count as if your are wielding it one handed.

If you have a chain or an enhanced rope available, then you can spend one long rest to attach it to a weapon and use all of your features. You can use a short rest to attach your chain/enhanced rope to your weapon, but can only attack once as a part of your single attack action (you will learn about this feature as you level up). 

If you do not have your chain/rope available, but have the materials, you can spend one long rest to craft enough to have 10 feet reach, total 3 long rests or one full day of uninterrupted crafting in a favorable smithing environment to complete 30 feet reach total. Or you can just buy it.

Bonus Proficiencies

At level 3, you gain proficiency in Smith's Tools.

You also gain proficiency in either Athletics or Acrobatics.

Chain Weapon Warrior

At level 3, you learn the art of using chained weapons and have a total reach of 10 feet on your weapon.

You can ignore half cover while making attacks with your chain weapon if you are wielding it with two hands. 

Your reach for opportunity attacks is still limited to your melee range + 5 feet. This stays same throughout all levels.

Retractive Strikes

At level 7, your total reach increases to 20 feet on your chain weapon.

Whenever you make an attack on any creature or an object, you can choose another target to make another attack as a part of the same attack action, as long as you are wielding your chain two handed, your attack on the first target was successful and the second target is within a cone of distance equal to the distance of the first target. This does not apply to opportunity attacks. The second target takes 1d4+modifier damage, irrespective of the weapon damage dice.

Any ability that lets you add extra damage only applies to the first creature you target. (Only additional weapon damage such as from a +1/+2/+3 weapon can be added to the second target, no other type of damage).

Chain Grappler

At level 7, you can use your chain to attempt to grapple someone at range. Subtract 5 feet from the length if the creature is small, 10 feet if it is medium and 15 feet if it is large. You cannot target a creature bigger than that.

As a bonus action, you can make a contested athletics check with the target you grappled where the one with the lower roll gets pulled towards the other covering distance equal to 15 feet or the difference between the contested rolls, whichever is higher. You can also choose to knock them prone instead if the difference between the contested rolls is 10 or higher.

You cannot use your chain weapon if you have someone grappled until they break free from your grapple or until someone else or you use their bonus action to free your weapon and any creature who does so cannot use any other object interactions until the start of their next turn unless they use their action.

You also get advantage on any checks involving ropes/chains (except for the ones in your chain grappler features).

Chained Defense

At level 10, your total weapon reach increases to 30 feet and the second target of same attack takes 1d6+modifier damage if your weapon damage die is a d6 or higher.

While wielding your chain weapon, you can use your reaction to get a bonus to your AC equal to your Dexterity modifier and you can do this a number of times equal to your proficiency bonus. This bonus lasts until the start of your next turn. You can also spend one use of this when you see another creature get attacked and give them the increase to AC instead, but the bonus will only last until the end of the attacker's turn.

You weapon now counts as a Great Weapon.

Improved Grappler

At level 10, you can use your reaction to throw your chained weapon and hook it to a surface within your chain weapons reach to stop yourself midfall by making a successful athletics or acrobatics check of DC chosen by your DM. You do get advantage on these checks.

You can also use it as a grappling hook as your bonus action and get climbing speed equal to your movement speed.

Effective Retractive Strikes

At level 15, your second target of your same attack will take weapon damage same as your weapon.

Your second target also gets affected by the damage that your weapon does by itself, but not by the damage that you have to willingly choose or add (Example: If your weapon does 1d4 fire damage with each attack, both the targets will get affected by that, but if you can choose to make that damage 2d4 for a certain time, it only applies to the first target, the second target still gets only 1d4 damage). You cannot implement any other condition or magical effect on the other target, only the base damage. If your weapon requires the target to make a saving throw, you cannot use that on the second target.

Balance Maneuver

At level 15, your ability to balance and maneuver such a long chain makes you better at maintaining your own balance. 

You gain proficiency in Dexterity saving throws.

Ultimate Chain Warrior

At level 18, your ability with your chain weapon to attack and defense reaches its utmost precision and speed. You can ignore three quarters cover while attacking with your chain weapon and can add your dexterity modifier to your AC even if you are wearing Heavy Armor as if it was Medium Armor, your chained defense stacks with this. You can also target a third target as a part of your Retractive Strike, on all attacks for a number of turns equal to your Dexterity modifier (minimum 1 turn). Same rules apply to the third target as they did for the second target.

Your reach increases to 40 feet while using your chain grappler features (for attack it is still 30 feet).