Allows you te set a page to be used as the 404 page. In order for the plugin to work you need to make some modifications to the <code>404.php</code> file in your theme. I set it this way so that the 404 page could be formatted to fit the theme, or can be set more dynamically.
For more information and sample code: http://www.reitzdesigns.com/2010/08/dynamic-404-page-wordpress-plugin/
Although this plugin will work with WordPress 2.8, it’s better suited for version 3.x.

Dynamic 404 Page

Allows you to select a page to use as the content of your 404 page.

socialdude

Try it out on your free dummy site: Click here => <a href="https://demo.tastewp.com/redirection" rel="nofollow ugc">https://tastewp.com/plugins/redirect-redirection</a>. 
(this trick works for all plugins in the WP repo – just replace “wordpress” with “tastewp” in the URL)
Create specific URL redirections and redirection rules super-easily on a beautiful, user-friendly interface of the Redirection plugin.
Creating even conditional redirections has never been easier and quicker than with the Redirection plugin.
Creating redirection has never been simpler, but for fine-tuning, you can use a wide choice of advanced options:
<ul>
<li>Redirect HTTP codes can be 301, 302, 303, 304, 307 and 308;</li>
<li>Inclusion and exclusion rules: logged in/out users, specific user role, user’s referrer link, user’s agent, user’s cookie, user’s IP, server, and language;</li>
<li>Redirection rules: Simplified redirection rules as well as advanced RegEx matches – URLs that contain specific string to new or removed string, URLs that start with X, specific permalink structures, RegEx matches, and 404s. Setting redirection rules with several matching conditions is also possible;</li>
<li>Managing all redirects comfortably – enable/disable, edit and delete redirects neatly listed in the plugin menu;</li>
<li>⭐️NEW! 404 page redirection to a Specific URL (e.g. homepage) or to a Random Similar Post;</li>
<li>⭐️NEW! Import/Export redirection lists (both Specific URL Redirections and Redirection Rules);</li>
<li>⭐️NEW! Redirection & 404 Logs – chronological log of all redirections and 404s with a one-click solution to add the redirection and fix the dead links;</li>
<li>Automatic redirects, Change URL – these features are coming soon!</li>
</ul>
This redirect plugin is part of the Inisev product family. Have a look at our <a href="https://inisev.com" rel="nofollow ugc">other projects</a> too please! 🙂

Dynamic 404 Page vs Redirection