I couldn't find your claim written anywhere Ponden ('halflings are supposed to get 15% bonus to death saves buffs in addition to the innate save').
I've written the fix, and I think its effects are logical. Note I didn't create the original effects, just making them work as they should.
There are now 4 separate death save types. Each is rolled separately, and happen in order. Obviously if one goes off, the others can't.
Death Save Buffs: All death save buff effects are added together, and the roll is made. If successful, you lose ALL death save buffs, and are healed to full. Chance of activating is based on the sum of the individual buffs.
Eternal Benevolence AA: It is VERY unlikely this will ever extend to non-clerics, but it is part of this none the less. The blow that SHOULD have killed you doesn't happen, and instead divine aura is cast on you, making you invulnerable, but unable to attack or cast. Chance of activation was broken, but is currently fixed at 2%/4%/6% depending on AA level.
Codex Save: When this fires off, the next swing to kill you misses, buying you maybe a chance to get a heal landed or something. The effect of this codex scales up from 0-10% depending on how filled the tome is, getting exponentially better til it reaches max.
Halfling Racial: Like the above, this one is a 15% chance that the next swing will not kill you, buying you a hit to hopefully find a more permanent solution to your dilemma. This is fixed at 15%.
Be aware that hit means ANY damage (except maybe fall damage, I didn't bother to check that). Back when the halfling racial worked, my rogue famously survived the AE death from running out of time on the Torment event.
This will hopefully go live this week, but I figured I'd keep you posted on the changes.
Also 1000th post!