Using Keyrune
Each set symbol has its own font character. Display them in a manner similar to Font Awesome using the <i class="ss ss-exp"></i> element. Class name codes are based on the expansion codes from MTG JSON.
To use Keyrune, move the font files to your /fonts directory and include the keyrune.css stylesheet in your <head>:
<link href="css/keyrune.css" rel="stylesheet" type="text/css" />
Insert set symbol icons by using the .ss class and then the set code class, such as .ss-mor for Morningtide: 
<i class="ss ss-mor"></i>