[BasilFawlty]

I took this as a challenge

NOTE - this first example placed the description just under the Thread Title, but since you wanted it under the Thread Reply button, do the first 5 steps, then skip to step #7.

Step 1: Open showthread.php for edit. Scroll down to the // output page section, look for this code: (It starts around line 2410-ish)

PHP Code:

$templater = vB_Template::create('SHOWTHREAD');
    $templater->register_page_templates();

    $templater->register('pagenumbers', fetch_start_end_total_array($vbulletin->GPC['pagenumber'], $perpage, $totalposts));
    $templater->register('totalposts', $totalposts);
    $templater->register('activeusers', $activeusers);
    $templater->register('ad_location', $ad_location);
    $templater->register('bookmarksites', $bookmarksites);
    $templater->register('editorid', $editorid);
    $templater->register('FIRSTPOSTID', $FIRSTPOSTID);
    $templater->register('firstunread', $firstunread);
    $templater->register('forumjump', $forumjump);
    $templater->register('forumrules', $forumrules);
    $templater->register('gobutton', $gobutton);
etc
etc
etc 


We first need to cause the variable $foruminfo to get "pushed" to the "SHOWTHREAD" template.

Step 2. Just above $templater->register('forumjump', $forumjump); ADD:
$templater->register('foruminfo', $foruminfo);

Step 3. Save and re-upload to your server

Step 4. Go to Admin CP >> Style Manage >> Edit Templates (for the style you want to modify - you'll need to do this for each style)

Step 5. Edit the "SHOWTHREAD" template (you may need to expand "Show Thread Templates" to see SHOWTHREAD (It will be all caps)

Step 6. Look for this code:

PHP Code:

<div id="pagetitle" class="pagetitle">
        <h1>
            {vb:rawphrase thread}: <span class="threadtitle"><a href="{vb:raw thread_url}" title="{vb:rawphrase reload_this_page}">{vb:raw threadinfo.title}</a></span>
        </h1>
        <vb:if condition="$show['fb_likebutton']">
            {vb:raw fblikebutton}
        </vb:if>
    </div> 


Just above the </div> tag add the following:

<p class="description">{vb:raw foruminfo.description}</p>

So the code will look like this:

PHP Code:

<div id="pagetitle" class="pagetitle">
        <h1>
            {vb:rawphrase thread}: <span class="threadtitle"><a href="{vb:raw thread_url}" title="{vb:rawphrase reload_this_page}">{vb:raw threadinfo.title}</a></span>
        </h1>
        <vb:if condition="$show['fb_likebutton']">
            {vb:raw fblikebutton}
        </vb:if>
<p class="description">{vb:raw foruminfo.description}</p>
    </div> 


I tried it on my forum and it seems to work. It places the forum description just under the thread title. However, since you wanted it just below the post reply button:

Step 7. (To place description below the Reply button instead): Look for:

PHP Code:

</div>
        <div id="pagetitle" class="pagetitle"> 


Step 8. Past the code between the </div> tag and the <div id="pagetitle" .... > tag, like this:

PHP Code:

</div>
    <p class="description">{vb:raw foruminfo.description}</p>
        <div id="pagetitle" class="pagetitle"> 


Step 9. Save and reload the template and test it out.

Hope this works for you.

Cheers,
Basil