Vampire achievement now changed to "In hard mode, steal 40% health"

Originally this achievement need to deal almost all damage to a boss with life steal effect active, this can be done in easy mode on some bosses. But only hard mode will display the life steal amount after defeat boss, which is confusing to player.

Adjusted hard mode difficulty, "Piece of Cake" achievement requirement for last 2 bosses can take up to 60 damage

"Piece of Cake" achievement is the most difficult one to achieve. It is designed to require player not only be familiar to all bosses and be quick in reflect, but also be very patient on their moves (do not take any unnecessary damage). Especially the last 2 bosses, in additional of all those, player also need some luck to be able to achieve. I understand the frustration when you did perfectly only failed due to not lucky enough (over and over again). Therefore I made these adjustment.