Embedded<T> — a collection keyed by the embedded object's own Guid Id

public class PriceTier {
    public Guid Id { get; set; }
    public string Name { get; set; } = string.Empty;   // "early bird", "standard", …
    public decimal Amount { get; set; }
}

public interface IEvent {
    // ...
    [EmbeddedProperty]
    Embedded<PriceTier> PriceTiers { get; }
}