Devil May Cry 4

Beat up to and including level 30 in Bloody Palace mode. To unlock Bloody Palace mode, beat the game on Devil Hunter difficulty. Do not quite the game, you need to die or finish all 101 floors to get the achievement. Below are a list of the enemies from waves 21-30:

21 Mephisto x2, Frost x1
22 Frost x2, Faust x1
23 Assault x3, Frost x2
24 Assault x 3, Basilisk x 4
25 Assault x3, Blitz x1
26 Blitz x1, Basilisk x4
27 Frost x2, Bianco Angelo x2
28 Assault x2, Gladius x8
29 Blitz x1, Gladius x5
30 Frost x4, Assault x6, Blitz x1