I picked up two Terra Tenebrosa shirts online recently from Debemur Morti Productions who just reissued their catalogue.
This one is for their second album, The Purging. The front print is of their frontman The Cuckoo with their TT logo in his forehead. The backprint is a large artwork print of The Purging album cover.
This is one of my favorite bands and I highly recommend checking them out. They formed after Swedens excellent band Breach broke up and are closely a continuation of that band to some extent. You can also still purchase these shirts directly from Debemur Morti Productions online if you like what you hear and see.