There's a helpful question spelling out how to use double square brackets [[]] to include card images, and triple square brackets [[[]]] to include links to card images: http://draw3cards.com/questions/234/how-do-i-enter-card-images-in-questions-and-answers
However, I've also seen people include links to card images from comments on questions and answers, where most formatting is disabled. See for example the comments at the top of http://draw3cards.com/questions/1526/best-walls-of-all-time . Mike1229 tried to include a link to a card with double square brackets [[]], but that didn't work. theatog was able to include a link to a card image in his reply.
I tried using triple square brackets [[[]]] in comments on this answer, but that didn't work either: http://draw3cards.com/questions/302/infinite-combo-in-current-standard-alara-zendikar-worldwake-rise-of-eldraz/1800#1800
I've had a look around, and can't find this explained anywhere. So the natural thing to do is ask it as a question.
Also, is the behaviour identical between [comments on questions] and [comments on answers]? I assumed it was, but thought I ought to check.
