Channel divinity(oath of vengeance) automatization

Greetings fellow DMs, I've found myself with this huge problem, I can't realize how to code this feature:
Abjure Enemy:
As an action, you present your holy symbol and speak a prayer of denunciation, using your Channel Divinity. Choose one creature within 60 feet of you that you can see. That creature must make a Wisdom saving throw, unless it is immune to being frightened. Fiends and undead have disadvantage on this saving throw.

On a failed save, the creature is frightened for 1 minute or until it takes any damage. While frightened, the creature's speed is 0, and it can't benefit from any bonus to its speed.

On a successful save, the creature's speed is halved for 1 minute or until the creature takes any damage.

I'm looking for a solution to fill the speed effect it imposes on the target. Help pls

I believe that is a paladin right? See this; https://www.fantasygrounds.com/forum...aladin-Package

If not, there is a similar thread for clerics.