From what I've heard. Tynon has calculations on heroes built into the game that reset daily. What's going around is pull some of your high runes at midnight from some like shayd and cianna. Then after reset before you put runes in go to heroics and face the bosses. Following that put your runes back on your heroes for improved % increase in facing them. Tynon having already giving you a set % for the day. The increase in power, etc.. actually improves your chances.
Just curious if anyone else knows this for sure. I mean it does make sense somewhat. When you kill a boss in 4 attempts one day, and the next day you have over 200 attempts and not dead yet(minister Lascivious). I figured i would check it out myself tonight, but out of curiosity decided to ask on forums.