Martial Archetype - Martial Legionnaire

Your training in martial techniques has made you a master of understanding how to observe, copy, and master the various techniques used by the warriors of Talerand. 

At 3rd level your limit on martial techniques you can use is doubled (proficiency modifier * 2). In addition you gain access to the following martial techniques

1. Shield Strike
2. Slide Tackle
3. Dirty Fighting

While in an area, you can spend 2 hours researching local martial technique masters and learn of their locations in order to seek their training. 

Starting at 7th level, when you observe a creature using a martial technique you may make an athletics or acrobatics check equal to 10 + the observed creatures CR to learn the martial technique they have used. Doing so permanently grants you access to that martial technique with no additional training required. Additionally, if the the observed technique utilizes a feature you don't have access to (Ex: Spell Slots) you may instead roll a D10 and subtract it from your max hit points in lieu of the required feature. These losses are returned on a short rest. 

At 10th level your study of martial techniques has granted you insight into the locations of masters who are able to train you in their usage even when they don't operate in the area you currently are in. When you do speak to a master you may also enact the code of mastery, which is a formal sparring challenge. The master chooses the stipulations of the match and if bested will provide you their martial technique at no charge (Time still applies). Both combatants must have at least a potion of healing to provide the loser as death in these challenges is still considered a crime and the use of outside intervention or abilities designated off limits during the duel lowers the disposition of the master and may incur other penalties.

Additionally, whenever you use a martial technique you may add your proficiency bonus to the damage to a creature once per turn. 

At 15th level you may blend certain techniques together. You gain the following abilities 

1. When using a technique that replaces your action you may instead use two attacks to activate it.
2. When using a technique that uses one of your attacks in the attack action, you may instead use a bonus action to activate.

At 18th level you gain the ability to create your own martial technique from your experience and mastery. Work with your DM on the actual creation of this technique.