You stand guard, a bulwark between your foes and your allies. Nobody can pass unimpeded by you. 

• Increase your Strength or Dexterity score by 1, to a maximum of 20.
• If you are wielding a Melee Weapon (does not include being unarmed), any creature of your choosing treats the melee reach of your weapon as difficult terrain, as long as you have your reaction available and you can see the creature.
• When you hit a creature with an opportunity attack, the creature's speed becomes 0 until the end of the current turn.

* This feat is intended as a replacement for Sentinel, as I find that Sentinel is a very niche and not well designed feat. Other than a few cases, the way D&D usually plays, unless you build specifically around it, Sentinel comes into play once on a blue moon. And when it does and does not function, it feels even more terrible. That's why I want to propose a change that would make it a little less powerful in the niche situations, but more applicable in more situations and actually fitting the flavour of what Sentinel was trying to do.

** This feat also chains into another feat - Relentless Sentinel.