FantasyAsset/Assets/Scripts/Abilities/AbilityInput.cs

using UnityEngine;

public class AbilityInput : MonoBehaviour
{
    [Header("User + Slots")]
    public AbilityUser user;
    public AbilitySlot[] slots = new AbilitySlot[4];

    void Update()
    {
        foreach (var s in slots) s?.Tick(Time.deltaTime);

        // Quick default bindings: 1..4
        if (Input.GetKeyDown(KeyCode.Q)) Use(0);
        if (Input.GetKeyDown(KeyCode.E)) Use(1);
        if (Input.GetKeyDown(KeyCode.R)) Use(2);
        if (Input.GetKeyDown(KeyCode.T)) Use(3);
    }

    public void Use(int index)
    {
        if (index < 0 || index >= slots.Length) return;
        slots[index]?.TryUse(user);
    }
}