by Lujo on Fri Apr 19, 2013 12:41 pm
No, you have to find that subdungeon in 3 different runs (at random) and touch the altar. I think the first time it appears is after you've unlocked 3 other altars, the second time after 6 and the third time after 8 (not sure though).
I almost got pwned by Shifty Brickwork!