Adds overall embed length check

src/Discord.Net.Core/Entities/Messages/Embed.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Immutable;
 using System.Diagnostics;
+using System.Linq;
 
 namespace Discord
 {
@@ -56,6 +57,8 @@ namespace Discord
             Fields = fields;
         }
 
+        public int Length => Title?.Length + Author?.Name?.Length + Description?.Length + Footer?.Text?.Length + Fields.Sum(f => f.Name.Length + f.Value.ToString().Length) ?? 0;
+
         public override string ToString() => Title;
         private string DebuggerDisplay => $"{Title} ({Type})";
     }

src/Discord.Net.Rest/Entities/Messages/EmbedBuilder.cs

@@ -11,6 +11,7 @@ namespace Discord
         public const int MaxFieldCount = 25;
         public const int MaxTitleLength = 256;
         public const int MaxDescriptionLength = 2048;
+        public const int MaxEmbedLength = 6000; // user bot limit is 2000, but we don't validate that here.
 
         public EmbedBuilder()
         {
@@ -169,6 +170,12 @@ namespace Discord
             for (int i = 0; i < Fields.Count; i++)
                 fields.Add(Fields[i].Build());
             _embed.Fields = fields.ToImmutable();
+
+            if (_embed.Length > MaxEmbedLength)
+            {
+                throw new InvalidOperationException($"Total embed length must be less than or equal to {MaxEmbedLength}");
+            }
+
             return _embed;
         }
         public static implicit operator Embed(EmbedBuilder builder) => builder?.Build();