StatBonus.cs

//DexStat.cs
using UnityEngine;

[DisallowMultipleComponent]
public class DexStat : MonoBehaviour
{
	public float dexStat = 100f;
}

...

//DexStatModifyer.cs
using UnityEngine;

[DisallowMultipleComponent]
public class DexStatModifyer : MonoBehaviour
{
	public float dexStatModifyer = 50f;
}

...

//DexStatSystem.cs
using UnityEngine;

public class DexStatSystem : EgoSystem<DexStat>
{
	public override void Start()
	{
		EgoEvents<AddedComponent<DexStatModifyer>>.AddHandler( ( e ) =>
		{
			var dexStatModifyer = e.component;
			ForEachGameObject( ( ego, dexStat ) =>
			{
				dexStat.dexStat += dexStatModifyer.dexStatModifyer;
			});
		});

		EgoEvents<DestroyedComponent<DexStatModifyer>>.AddHandler( ( e ) =>
		{
			var dexStatModifyer = e.component;
			ForEachGameObject( ( ego, dexStat ) =>
			{
				dexStat.dexStat -= dexStatModifyer.dexStatModifyer;
			});
		});
	}
}