Mastery of the Spear Master
Unrivalled is their skill with a spear. The Spear Master is agile and quick to such a degree that witnesses say they are but a blur. It takes patience, strength, an iron will and many years of training to become a master of the spear. Spear Masters frequently take the front line, striking fast and accurately, aiming for weak spots, slits, and gaps in enemies' armor. They are aggressive but can be defensive if the need arises. Generally, a Spear Master has started their training early enough to reach the level of master in their physical prime. Spear Masters can be found as captains of a royal guard, or the personal guard of a merchant, or even a leather worker in a small town who wants to lead a simple life. Not all Spear Masters aim for wealth and glory, but rather a meaningful life, they tend to keep their skills unknown to stranger.
Warden's Rebuke
Starting at 3rd level, you can avenge attacks made against your allies. Whenever you are wielding a spear, trident or javelin and a friendly creature within 5 feet of you is hit by a melee attack, you can use your reaction to make an opportunity attack against the attacker. The creature is considered within your reach for melee attacks even if it wouldn't normally.
Sentinel Strike
Also at 3rd level, you can make opportunity attacks using your spear, javelin, or trident without using a reaction. You can use this feature a number of times equal to your proficiency bonus and regain your uses of it after a long rest.
Spear Mastery
When you choose this archetype at 3rd level, your attacks made with spears, tridents and javelins increase to 1d8, and the damage for spears and tridents wielded in two hands increase to 1d10. You can use your Strength or Dexterity modifier for attack rolls made with these weapons. In addition, when you wield a spear or a trident in two hands, they acquire the reach property.
Vigilant Guard
Spear Masters are alert and have quick reflexes. At 7th level, you gain proficiency in Perception. If you already have proficiency in this skill, you can add twice your proficiency bonus in checks with it. In addition, you gain proficiency in Dexterity saving throws.
Intercepting Strike
Starting at 10th level, when you or a creature within 5 feet of you takes damage from a melee weapon attack, you can try to intercept that attack with your spear. You roll the damage for your attack, and reduce the damage taken by the amount rolled. If you reduce the damage to 0, you can use your Warden's Rebuke feature as part of the same reaction.
Keen Spearman
At 15th level, you score a critical hit on a 19 or 20 with your attacks. On a critical hit, you roll the damage of your weapon two times.
Whirlwind Spear
When you reach the 18th level, you become a true spear master. When you take the Attack action, you can forgo all your attacks to make one attack against each creature of your choice within your reach.