gather-and-defend/Assets/Scripts/Status/Slow.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Slow : Status
{
    private float _previousSpeedModifier = 1f;
    private float _speedModifier = 1f;

    public override void Apply(float duration)
    {
        // reset slow duration
        _duration = Mathf.Max(_duration, duration);

        // slow entity
        EntityLinked.SpeedStatusModifier /= _previousSpeedModifier;
        EntityLinked.SpeedStatusModifier *= _speedModifier;
    }

    public override void Unapply()
    {
        // bring entity to normal speed
        EntityLinked.SpeedStatusModifier /= _speedModifier;

        // stop effect
        Destroy(this);
    }

    /// <summary>
    /// A higher intensity results in a stronger slow.
    /// Example: An intensity of 0.99 multiplies the entity's speed by 0.01 (which would result in a really low speed)
    /// </summary>
    public float Intensity
    {
        get => 1 - _speedModifier;
        set
        {
            _previousSpeedModifier = _speedModifier;
            _speedModifier = Mathf.Min(_speedModifier, 1 - value);
        }
    }
}