Not trying to brag, but I got 2 mono element set DFs on my last open of 11 chests. The previous 3 times I opened 11 at once I got 3 & 4* armors and one or two old epics. There aren't many 3* armors in the game (8 according to the database of armors), so pulling the same one 4 times in a row isn't unlikely.
Just like a guy i know pulled 3 haomas in 11. Then you watch vids on youtube of them getting crap(most of the time) and end up wanting to chance. It's subliminal messaging at its finest.