So one of the neat things in tome of excess is that having more advances by your god's favorite number (or greater) then any other type gives you a little perk. they all take the form of adding 1 to a characteristic bonus in a specific situation. But while i can see the use for the Khorne, Slaanesh and Tzeentch bonus, i can,t figure any benefit from improved characteristic bonus for the Nurgle number.
It says that your Toughness Bonus counts as one higher when resisting toxins and poisons. But all the effects I've seen that match that descriptor are a pass/fail effect, where you avoid the completely, or suffer the full effect, and i cant figure what benefit your supposed to get.
for reference, the other number bonuses of the gods are
Tzeentch : +1 Willpower Bonus on opposed willpower tests with psychic powers (helps you win on ties)
Khorne: +1 Weapon skill bonus for multiple hits in melee (WS bonus determines the max number of hits possible for lighting and swift attack.)
Slaanesh: +1 Perception Bonus on any tests related to the 5 senses (helps you win on ties for any skill opposed with perception)