relics/RelicLoveLetter.cs
using Sandbox;
using System.Reflection.PortableExecutable;
using System.Runtime.Versioning;
using System.Threading.Tasks;

public class RelicLoveLetter : Relic
{
	public override bool ShouldHandleEvent( EventType eventType )
	{
		return eventType == EventType.GainHP && Manager.Instance.Stats[StatType.LatestHealAmount] > 0f && Game.Random.Float(0f, 1f) < (0.20f * Level);
	}

	public override async Task HandleEventAsync( EventType eventType )
	{
		var validCards = Manager.Instance.Cards.Where( x => !x.IsRevealed ).ToList();
		if ( validCards.Count == 0 )
			return;

		await Task.DelayRealtime( 250 );

		Manager.Instance.PushEventMessage( this, eventType );

		Card cardToReveal = validCards[Game.Random.Int( 0, validCards.Count - 1 )]; ;

		Manager.Instance.PlayCardSfx( "love_letter", cardToReveal, volume: 1.1f, pitch: Game.Random.Float( 0.95f, 1.05f ) );

		await Task.DelayRealtime( 200 );

		Manager.Instance.PlayCardSfx( "card_flip", cardToReveal, volume: 0.8f, pitch: Game.Random.Float( 1.15f, 1.2f ) );
		await Manager.Instance.RevealCard( cardToReveal );

		await Task.DelayRealtime( 900 );

		//Manager.Instance.PlayCardSfx( "flashlight", this, volume: 1.2f, pitch: Game.Random.Float( 0.75f, 0.8f ) );

		await Task.DelayRealtime( 350 );

		Manager.Instance.PlayCardSfx( "card_flip", cardToReveal, volume: 0.7f, pitch: Game.Random.Float( 0.65f, 0.75f ) );
		Manager.Instance.HideCard( cardToReveal );

		await Task.DelayRealtime( 200 );

		Manager.Instance.PopEventMessage();
	}
}