The Tome of Battle is one of the Vestiges of Divergence Prime, explicitly created to defend the Celestial Gate. This ancient tome  contains a detailed explanation and analysis of the combat specialist, from weapons and strategy to the importance of intelligence, tactics, and discipline. It contains the secrets of the Swordsage and the magical runes used to enhance reverend weapon. If you spend 24 hours studying the book's contents you open the initial magic of the book,  Considered in its Dormant state you learn the first runic secrets and how to magically inscribe them on your chosen weapon. This weapon counts as magical for the purpose of overcoming resistance and immunity to nonmagical attacks and damage. You may only have one reverend weapon at a time.  You can choose to change your weapon for another weapon  through a 24 hour ritual that destroys the original weapon allowing you to inscribe a new one. Upon becoming attuned to the tome you gain the following benefits.

    Eternal Knowledge: You gain proficiency in the Insight skill if you do not already have it.

  Blade Guide: You gain a blade guide, the spirit of an ancient member of the eternal blades, that provides you with advice, tactical assistance, and training. The blade guide is incorporeal, has hit points equal to your own, and is size Fine. Its AC is 18, and it can fl y with perfect maneuverability and a speed of 30 feet. If your blade guide is destroyed, or it somehow moves out of your line of sight, it reappears in your space in 1d6 rounds. The guide is the physical manifestation of a spirit that resides on the Outer Planes. Destroying a blade guide’s form merely severs its link to the Material Plane for a short time. A blade guide appears as a mote of white energy. It uses your senses to see and hear, and communicates with you by telepathy. Thus, it cannot interact with objects and creatures that you cannot see. Your blade guide is meant to aid you in combat, not serve as a scout. Sometimes, your guide appears as a ghostly image of how it looked in life. This manifestation requires tremendous effort, and your guide chooses to attempt it only when it must communicate with others under dire circumstances. When a blade guide manifests, it can speak with others as normal. A blade guide can appear in this manner for up to 10 minutes per day. While it manifests, you lose access to your blade guide and any abilities that require it to function. If a blade guide must make a saving throw, it uses your save modifier. It lacks skill ranks, feats, Hit Dice, and ability score modifiers.

Eternal Training: Your blade guide offers you intense martial training based on its years of combat experience in mortal life. Each night, your blade guide enters your mind. In your dreams, the two of you spar and practice across a hundred different battlefields, and fight monsters that your guide creates from the ether of dreams. You practice maneuvers beyond your normal capacity. With each night that passes, you become more and more skilled in the fighting arts.You can draw upon this nightly training to aid you in a battle. You can choose one of two benefits:

                Insightful Strike: You make a melee attack. If this attack hits, you do not deal normal damage. Instead, you make a Concentration check and deal damage equal to the check result. Your Strength modifier, your weapon’s magical properties (if any), and any other extra damage you normally deal does not modify this check (including extra damage from class abilities, feats, or spells).

Mind Strike: You make a melee attack. If this attack hits, your target must make an Int. save against your spell save DC, or suffer double damage (all modifiers and magic bonuses included) from the attack. If the target successfully saves it takes weapon damage normally.

You can access your eternal training a number of times per day equal to your proficiency modifier. You can use this ability only while you have access to your blade guide.

After training with Your Blade Guide and you become more adept at applying the knowledge you have received, you will awaken the following abilities:

       Guided Strike: Your blade guide assesses your enemies, seeking out weak points in their armor and offering you advice on where and how to strike. Drawing on its experience and keen eye for strategy and tactics, your guide grants you advice that can render even the most daunting foe impotent. You can as a bonus action confer with your guide concerning a single foe that you face. Until the end of your next turn, you automatically overcome any of your foe’s damage immunity's or resistances, if any. This ability a number of times per day equal to your proficiency modifier. You can use this ability only while you have access to your blade guide.

         Insightful Dodge: So long as your blade guide is active, you gain the benefit of uncanny dodge (when an attacker that you can see hits you with an attack, you can use your reaction to halve the attack’s damage against you.) This ability can be used a number of times per day equal to your proficiency modifier. You can use this ability only while you have access to your blade guide.

          Defensive Insight: Your blade guide’s advice and insights grant you an intellectual edge in combat, but there is a fine line between knowing how to do something and executing it in combat. If you take a moment to focus yourself, you can apply your knowledge to the situation at hand., as a bonus action, you can use your tactical knowledge against your foes. You gain a bonus to AC equal to your Intelligence bonus (if any) until the beginning of your next turn. This ability can be used a number of times per day equal to your proficiency modifier. You can use this ability only while you have access to your blade guide.

Finally after a substantial time of training with your Blade Guide you unlock the legendary potential of the tome and his teachings, you gain the following abilities:

       Tactical Insight: Your blade guide lends you the experience and wisdom of one who has fought battles across countless fields. In almost any situation you face, you have the experience, tactical lore, and knowledge needed to defeat your enemy. On the battlefield, you are a leader. You issue orders and coordinate your allies, but you also learn to take advantage of their actions and maximize the fruits of teamwork. When you attack a foe with your allies, the combined result of your efforts can be devastating. Chose from one of the three following actions:

                   Following Up: To use this option, you must make a successful DC 20 Insight check as a Bonus action after hitting your target with a melee attack. If you hit that target, the target provokes an attack of opportunity from all of your allies that threaten the target. (assuming they have a reaction to use).

                 Perpetual Flank: To use this option, as a bonus action you make a DC 20 Intimidate check against an opponent. If this check succeeds and you make a successful melee attack, you and your allies advantage against that enemy until the end of your next turn.

                Pile On: To use this option, you must use the aid another action to grant an ally advantage on his next attack roll against an opponent both of you threaten. If your ally attacks and hits that enemy, you can take an immediate reaction against that target. You gain this benefit if your ally hits the foe before the start of your next turn.

Tactical Insight can be used a number of times per day equal to your proficiency modifier. You can use this ability only while you have access to your blade guide.

       Island in Time: You can throw yourself into a fight under your blade guide’s careful direction. You meld with it, allowing it to control your actions while you draw upon its vast combat experience. Once per encounter, you can take your turn as Legendary action. Using this ability does not change your initiative count, and you can use all your actions as normal. For example, if your initiative count is 15, you could act normally, use this ability to act again on initiative count 14, then act normally on the following round on initiative count 15. If you lose access to your blade guide, you lose this ability until it returns. This ability resets after a long rest.

Notes: Proficiency: Insight, Fighter, Buff