Martial Archetype: Strategist

The strategist is a type of fighter who knows that victory cannot always be won by blindly attacking your foes. Either through academic research or finely honed instinct, the strategist knows that an enemy will reveal their weaknesses in time, all you have to do is watch and wait. But once an opening is revealed, the Strategist (AND the whole party!) will be able to strike with greater precision.

Astute Warrior

When you choose this archetype at 3rd level, you gain two of the following skills : Arcana, History, Insight, Investigation, Nature, or Perception.

Helping Hand

At 3rd level, you may use Help as a bonus action. You may grant this help either by being within 5 feet of your ally, or within 5 feet of their target (you may move away after declaring you've used the Help action), giving the ally advantage on their first attack roll on their next turn. You may use this ability once per short or long rest. You gain additional uses of this feature at levels 7 and 15.

Exploit Weakness

At 7th level, you begin to put battle theory into practice, and study your foes' tactics and weaknesses. When in combat, you may forgo your bonus action and one of your Extra Attacks for 2 consecutive rounds to focus on observing your enemy. On the start of your 3rd turn after using this ability, you and any allies within 30 feet who can see or hear you gain +2 to attack and damage rolls, and +1 to AC and saving throws against the foes' attacks for the rest of combat. Exploit Weakness ends early if you are incapacitated. At 18th level, the buffs from this feature increase by 1, and the effective range becomes 60 feet. You must take a short or long rest before using this feature again.

Expertise

Starting at 10th level, you may double your proficiency bonus for any 2 skills you already have.

Sit and Watch The Strategist trades some action economy for a greater offensive potential in the long term. However, note the word "some". You can still start using most of your abilities and still get an attack off for a couple turns before an ability can fully activate and buff you or your team. Also, a Strategist's patience is rewarded by not multiclassing, as each ability gets stronger at later levels.

Turn the Tide

Also at 10th level, you begin to learn how to circumvent an enemy's natural defenses. Starting on your turn of the 2rd round of combat, you may use your action to study a foe with either an Arcana, History, Insight, Investigation, Nature or Perception check, whichever the DM deems appropriate. The DC for this check is the Creature's CR + 5 (The DM is free to adjust this number, but must tell you the DC). This check automatically succeeds on a creature who's CR is less than half your level. If the check is successful, you glean some insight as to how to hit your foe more effectively, and are able to plan your next moves accordingly. Your attacks against that foe and any like it ignore resistance (but not immunity) until the end of your next turn. At 18th level, you have advantage on this check, and immunity to damage is changed to half damage. You have unlimited uses of this feature.

Martial Mastery

As a student of all forms of martial combat, you've sought to emulate the techniques of your peers. At 15th level, choose another Martial Archetype: Champion, Battle Master, Eldrich Knight, or any other archetype that your DM will allow: You gain all starting level 3 abilities for that archetype.

One for the Team

Sometimes, the best way to motivate people is to give them something to avenge. Starting at level 18, if your HP ever reaches 0 and you are incapacitated, any allies within 90 feet who can see you (even if incapacitated) may choose to instantly receive all the benefits of a short rest, and may expend a number of Hit Dice equal to half your Fighter Level to regain hit points. They also gain +10 speed, and Advantage on attacks and saving throws against whatever killed you for 1 minute, or until you are revived, whichever happens first. After combat, anyone who benefited from this feature suffers 1 level of exhaustion. You may only use this feature once per in-game week.