This idea came right after Enter the Jade Empire who had the highest possible DC for stunning attack. So I present you with the Highest possible DC for Death attack. A True Assassin, solo you are a devastating killer. You appear out of no where to slay the mightiest foe. In groups you and other assassins unleash a flurry of attacks that leave bodies laying everywhere.
Snake Eyes


Advantages
20d6 Death Attack With DC of 52
Hide In Plain Sight
Ooodles of Skill Points
8 Attacks

With +12 Int Items DC becomes 58

Disadvantages
Lowish HP 340 Max
Lowish AC
Special Ability useless vs. Immune to Mind/Evil Creatures
Weak Vs. Immune to Sneak Attack Creatures

Human Lawful Evil

Monk9/ShadowDancer1/30 Assassin

Starting Stats/Ending
STR 8/8
DEX 16/16
CON 12/12
WIS 8/8
INT 18/34
CHA 8/8

Stat Progression
All go into INT

Level/Feat Progression
1 MNK – Dodge, Mobility
2 MNK –
3 MNK – Weapon Finesse
4 MNK – INT
5 MNK –
6 MNK – Ambidextrous
7 MNK –
8 MNK – INT
9 MNK – Two Weapon Fighting
10 SHD –
11 AS –
12 AS – INT, Improved Two Weapon Fighting
13 AS –
14 AS –
15 AS – Weapon Focus (Kama)
16 AS – INT
17 AS –
18 AS – Toughness
19 AS –
20 AS – INT
21 AS – Greater INT I
22 AS –
23 AS –
24 AS – INT, Greater INT II, Epic Skill Focus (Move Silently)
25 AS –
26 AS –
27 AS – Greater INT III
28 AS – INT, Improved Sneak Attack I
29 AS –
30 AS – Greater INT IV
31 AS –
32 AS – INT, Improved Sneak Attack II
33 AS – Greater INT V
34 AS –
35 AS –
36 AS – INT, Greater INT VI, Improved Sneak Attack III
37 AS –
38 AS –
39 AS – Improved Sneak Attack IV
40 AS – Improved Sneak Attack V

Miss something? Running out of ideas here.

Edit : Stat allocation Toughness needs to be switched with Imp 2 Wpn fighting for BAB requirements. I have a revised version of Snake Eyes, the previous one was geared for the highest DC for a Death attack, but lacked in other areas. The result, 8-10 15d6 Sneak Attacks per round to the poor soul that fails a 43 DC Fortitude Save.

Snake Eyes V2.0

Advantages
43 Death Attack DC (Ver1.0 had 53)
34 Naked AC (Ver1.0 had 24)
45 AB (Ver1.0 had 34)
15d6 Death Attack (Ver1.0 had 20d6)
HIPS

Attack Sequence w/2 Mundane Kamas
43/40/37/34/31/28
43/40

Disadvantages
Weak Vs Immune to Sneak Attack
Low HP

Race Halfing
Alignment Lawful Evil

Starting/Ending Stats
STR 6/6
DEX 20/40
CON 12/12
INT 16/16
WIS 8/8
CHA 8/8
Stat Progression
All into Dex

LvL Progression
MNK-Dodge
MNK-
MNK-Wpn Finesse
MNK-
MNK-
MNK-Mobility
AS-
AS-
AS-Weapon Focus (Kama)
AS-
AS-
AS-Ambidexterity
AS-
AS-
AS-Two Weapon Fighting
AS-
MNK-
MNK-
MNK-Improved Two Weapon Fighting
MNK-
20AS-
21AS-Epic Prowness
22AS-
23AS-Great Dex I
24AS-Epic Weapon Focus (Kama)
25AS-
26AS-
27AS-Great Dex II, Great Dex III
28AS-
29AS-
30AS-Great Dex IV
31AS-Great Dex V
32AS-
33AS-Great Dex VI
34AS-
35AS-Great Dex VII
36AS-Great Dex VIII
37AS-
38AS-
39AS-Great Dex IX, Great Dex X
40SHD- I goofed.
The shadowdancer level has to be taken at lvl 10.