cards/CardRedEnvelope.cs
using Sandbox;
using System.Net;
using System.Threading.Tasks;

public class CardRedEnvelope : Card
{
	public override bool ShouldHandleEvent( EventType eventType )
	{
		switch ( eventType )
		{
			case EventType.Match:
				return Manager.Instance.ChosenCards[1] == this;
		}

		return false;
	}

	public override async Task HandleEventAsync( EventType eventType )
	{
		Manager.Instance.PushEventMessage( this, eventType );

		await Task.DelayRealtime( 50 );

		Manager.Instance.PlayCardSfxBetween( "red_envelope", Manager.Instance.ChosenCards[0], Manager.Instance.ChosenCards[1], volume: 1.2f, pitch: Game.Random.Float( 1.0f, 1.05f ) );

		await Task.DelayRealtime( 100 );

		if (Manager.Instance.Money < 5)
		{
			await Task.DelayRealtime( 500 );

			Manager.Instance.PlayCardSfxBetween( "coin", Manager.Instance.ChosenCards[0], Manager.Instance.ChosenCards[1], volume: 1.4f, pitch: Game.Random.Float( 0.9f, 1.1f ) );

			await Task.DelayRealtime( 50 );

			int moneyAmount = (5 - Manager.Instance.Money) + (int)Manager.Instance.Stats[StatType.EarnExtraMoney];

			Manager.Instance.SpawnGainMoneyFloater( moneyAmount, WorldPosition );

			await Manager.Instance.GainMoney( moneyAmount );

			await Task.DelayRealtime( 200 );
		}

		await Task.DelayRealtime( 500 );

		Manager.Instance.PopEventMessage();
	}
}