1. Aligned with naming standards

2. Clarified xml docs
3. Properly threw exceptions instead of failing silently.

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

@@ -58,13 +58,16 @@ namespace Discord
         Task UnpinAsync(RequestOptions options = null);
 
         /// <summary>
-        ///     Publish this message when executed in a News Channel.
+        ///     Publish (crosspost) this message.
         /// </summary>
         /// <param name="options">The options to be used when sending the request.</param>
         /// <returns>
         ///     A task that represents the asynchronous operation for publishing this message.
         /// </returns>
-        Task PublishAsync(RequestOptions options = null);
+        /// <remarks>
+        ///     Publishing (crossposting) is only available in news channels.
+        /// </remarks>
+        Task CrosspostAsync(RequestOptions options = null);
 
         /// <summary>
         ///     Transforms this message's text into a human-readable form by resolving its tags.

src/Discord.Net.Rest/DiscordRestApiClient.cs

@@ -695,7 +695,7 @@ namespace Discord.API
             var ids = new BucketIds(channelId: channelId);
             await SendAsync("POST", () => $"channels/{channelId}/typing", ids, options: options).ConfigureAwait(false);
         }
-        public async Task PublishAsync(ulong channelId, ulong messageId, RequestOptions options = null)
+        public async Task CrosspostAsync(ulong channelId, ulong messageId, RequestOptions options = null)
         {
             Preconditions.NotEqual(channelId, 0, nameof(channelId));
             Preconditions.NotEqual(messageId, 0, nameof(messageId));

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

@@ -286,13 +286,13 @@ namespace Discord.Rest
             return MessageSource.User;
         }
 
-        public static Task PublishAsync(IMessage msg, BaseDiscordClient client, RequestOptions options)
-            => PublishAsync(msg.Channel.Id, msg.Id, client, options);
+        public static Task CrosspostAsync(IMessage msg, BaseDiscordClient client, RequestOptions options)
+            => CrosspostAsync(msg.Channel.Id, msg.Id, client, options);
 
-        public static async Task PublishAsync(ulong channelId, ulong msgId, BaseDiscordClient client,
+        public static async Task CrosspostAsync(ulong channelId, ulong msgId, BaseDiscordClient client,
             RequestOptions options)
         {
-            await client.ApiClient.PublishAsync(channelId, msgId, options).ConfigureAwait(false);
+            await client.ApiClient.CrosspostAsync(channelId, msgId, options).ConfigureAwait(false);
         }
     }
 }

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

@@ -148,12 +148,15 @@ namespace Discord.Rest
             TagHandling roleHandling = TagHandling.Name, TagHandling everyoneHandling = TagHandling.Ignore, TagHandling emojiHandling = TagHandling.Name)
             => MentionUtils.Resolve(this, 0, userHandling, channelHandling, roleHandling, everyoneHandling, emojiHandling);
 
-        public async Task PublishAsync(RequestOptions options = null)
+        /// <inheritdoc />
+        public async Task CrosspostAsync(RequestOptions options = null)
         {
-            if (Channel.GetType() == typeof(RestNewsChannel))
+            if (!(Channel is RestNewsChannel))
             {
-                await MessageHelper.PublishAsync(this, Discord, options);
+                throw new InvalidOperationException("Publishing (crossposting) is only valid in news channels.");
             }
+
+            await MessageHelper.CrosspostAsync(this, Discord, options);
         }
 
         private string DebuggerDisplay => $"{Author}: {Content} ({Id}{(Attachments.Count > 0 ? $", {Attachments.Count} Attachments" : "")})";

src/Discord.Net.WebSocket/Entities/Messages/SocketUserMessage.cs

@@ -147,16 +147,19 @@ namespace Discord.WebSocket
         public string Resolve(TagHandling userHandling = TagHandling.Name, TagHandling channelHandling = TagHandling.Name,
             TagHandling roleHandling = TagHandling.Name, TagHandling everyoneHandling = TagHandling.Ignore, TagHandling emojiHandling = TagHandling.Name)
             => MentionUtils.Resolve(this, 0, userHandling, channelHandling, roleHandling, everyoneHandling, emojiHandling);
-        
-        private string DebuggerDisplay => $"{Author}: {Content} ({Id}{(Attachments.Count > 0 ? $", {Attachments.Count} Attachments" : "")})";
-        internal new SocketUserMessage Clone() => MemberwiseClone() as SocketUserMessage;
 
-        public async Task PublishAsync(RequestOptions options = null)
+        /// <inheritdoc />
+        public async Task CrosspostAsync(RequestOptions options = null)
         {
-            if (Channel.GetType() == typeof(SocketNewsChannel))
+            if (!(Channel is SocketNewsChannel))
             {
-                await MessageHelper.PublishAsync(this, Discord, options);
+                throw new InvalidOperationException("Publishing (crossposting) is only valid in news channels.");
             }
+
+            await MessageHelper.CrosspostAsync(this, Discord, options);
         }
+
+        private string DebuggerDisplay => $"{Author}: {Content} ({Id}{(Attachments.Count > 0 ? $", {Attachments.Count} Attachments" : "")})";
+        internal new SocketUserMessage Clone() => MemberwiseClone() as SocketUserMessage;
     }
 }