(
I have no idea if this works in Internet Explorer. It may even balls up the whole of DT for you. If so, sorry! Tested it: seems to work fine.)
When you're writing a post if you enter code like this:
<span class="card">Demonic Tutor</span>
You will get this:
Demonic Tutor
(Hover your mouse over to see the goodness.)
You can also combine with a link (or any other HTML element):
<a class="card" href="http://magic.bluebones.net/proxies/">Teferi, Mage of Zhalfir</a>
becomes:
Teferi, Mage of Zhalfir
Which is to say that it's the 'class="card"' bit that does the magic.
Let me know how you get on with it, especially if it doesn't work in your browser.