Maven (Mastermind Variant)

Maven.

Defined as: "one who is experienced or knowledgeable."

Rogues who embrace this archetype are confidantly talented, remarkably knowledgeable, and excel in being flexibly useful in any and all situations. The secret to their success is their cunning attitude and their ambitious energy. Energy in which they focus into a means of success. Many spies, courtiers, and schemers follow this archetype, leading lives of intrigue.

Maven's Savvy

At 3rd Level, a wellspring of ingenuity flows within yourself, manifesting as focused energy.

This focused energy is represented by your Savvy dice, which are each a d6. When you reach certain levels in this class, the size of your Savvy dice increases: at 5th level (d8), 11th level (d10), and 17th level (d12). You have a number of these dice equal to twice your proficiency bonus, and they fuel various benefits you have, which are detailed below.

Calculated Callsign. Your helping hand extends to support your allies through a tactical signal. A creature within 60 ft. of you can be targeted by your Help Actions as though it were within 5 ft. of you, but only if the targeted creature can see or hear you. Additionally, you can take the Help Action as a Bonus Action.
Upon taking the Help Action, you can roll a Savvy die and add the number rolled to the attack roll or ability check you are intending to grant advantage to. The die is expended only if the attack hits or if the check succeeds.

Efficient Effort. You exort more effort when helping out in scenarios in which you are most needed. If you make an ability check using a skill or tool with which you are proficient, you can roll one Savvy die and add the number rolled to the check. The die is expended only when the check succeeds.

Fortuitous Fluidity. You are prepared to shift from plan to plan at a moment's notice. If the triggering effect of a Reaction you can take occurs and you have already taken your Reaction, you can expend one Savvy die to take that Reaction. Once you take a Reaction in this way, you cannot do so again until after the start of your next turn. You can use only one Reaction per triggering effect.

You regain all your expended Savvy dice upon finishing a long rest.

Gifts of the Cunning

At 3rd level, you develop and master once dormant talents that will be thoroughly used to your advantage.

You gain proficiency in three skills or tools of your choice, and your proficiency bonus is doubled for one skill or tool of your choice with which you are proficient. Additionally, you gain proficiency in using Vehicles (Land and Water) if you don't already have it.

Sharp Hustle

At 9th level, your maneuvering, much like your acuity, becomes sly and quick.

Your movement speed gains a +10 ft. bonus, and you gain a climbing and swimming speed equal to your movement speed. 
Additionally, when a creature willingly moves into a space within 5 ft. of you on its turn, you can use a Reaction to move up to half your movement speed and make one weapon attack against it. This movement does not provoke Opportunity Attacks, and your attack can be made before, during, or after your movement. On a hit, your target's movement speed becomes 0 until the end of its turn, and you can expend one Savvy die, as part of the hit, to deal an additional amount of damage equal to a roll of the expended Savvy die.  

Tandem Tactician

At 13th level, you excel at using teamwork to your advantage.

Once on each of your turns, when you target a hostile creature with the Help Action intending to grant advantage to one attack roll made against it, you can expend one Savvy die to make one weapon attack against your target, as part of the same action, so long as it is within range. The attack roll of a weapon attack made in this way is made with advantage and, on a hit, your target suffers from the following additional penalties:

• Your target is dealt an additional amount of damage equal to a roll of one Savvy die.
• Your target becomes easier to strike, as all attack rolls against it are made with advantage until the start of your next turn. Once per turn, when your target takes damage from a creature other than yourself within this duration, it is dealt an additional amount of damage equal to a roll of one Savvy die.

Masterful Maven

At 17th level, your mastery in all things is not only abundant, but also unmatched.

You gain the following benefits: 

Ace of Trades. Your cunning knows no bounds. You gain proficiency in three skills or tools of your choice, and your proficiency bonus is doubled for one skill or tool of your choice with which you are proficient. 

Reliable Savvy. Whenever you would expend a Savvy die for a feature in this class, you can roll a d6 and use it instead of expending a Savvy die. However, any additional damage dice dealt by the affected feature are replaced by d6 dice. For instance, if you are a 17th level Rogue and you roll a d6 instead of expending a Savvy die for an instance of your "Tandem Tactician" feature, any additional damage dice dealt by that feature are d6's instead of d12's.

Tactical Advantage. No opportunity to turn the tables goes unnoticed by you. If at least one of your allies is within 5 ft. of a creature and the ally isn’t incapacitated, your movements cannot provoke its Opportunity Attacks and you have advantage on any attack roll you make against it.
Furthermore, if weapon attacks you make against a creature would result in a Sneak Attack due to having advantage that is granted by this benefit, any weapon attack you make through your "Tandem Tactician" feature against that creature cannot miss regardless of the roll, and on a hit, the attack deals an additional amount of damage equal to a roll of two Savvy dice.