Dismounting (5e Variant Rule)
From D&D Wiki
A weapon with the dismounting property is a polearm with a hook designed for pulling riders from their mounts.
When you hit a creature on a mount, you can choose to deal no damage and pull the target. If you do so, the target must make a Dexterity saving throw to stay mounted, as though he had been knocked prone (PHB p. 198).
|Guisarme||10 gp||1d8 piercing||5 lb.||Heavy, dismounting, reach, two-handed|