Halberdier: balance opportunity attack with unseat dat horseman

PIkeman / halberd style fighting against cavalry:

This weapon allowed a good pikeman the ability to fight one-on-one with a mounted and fully armed knight and win. The weapon is wonderfully designed to de-horse a knight and deliver a killing blow with as little as one fluid motion. The weapon is made to hook the neck or head of the knight as the pikemen side-steps the charge. They can pull down the knight to the ground and with the spike on the back of the weapon, pierce the armor and go for the kill. This ability to pierce with either the small spike or the spear head allowed a pikemen to fell heavy infantry and even those wearing heavy plate armor. Also available to the pikemen is the spear-tip at the end as well as the ax end. This is likely the most advanced spear ever created for use by an individual soldier.

https://www.quora.com/Why-were-pikemen-like-the-Landsknecht-so-effective-in-early-renaissance-warfare

since1968 / statblocks

Halberdier: balance opportunity attack with unseat dat horseman #2