lets say you have Breath of the dying with 100min 500max dmg. Your max damage would be calculated as following:
Your vengeance skill adds 200% each type of elemental damage. This will lead to maximum dmg of: 500max physical, 1000 fire dmg 1000 light dmg 1000 cold dmg. --> 3500max dmg.
Above it is correct that Grief isn't usable cuz of how the +dmg works.
Quote
The following factors count toward Vengeance elemental damage, increasing the power of elemental bonus attack:
On-weapon ED%.
On-weapon +min/+max damage.
+min/+max damage in off-weapon equipment (such as War Traveler, Bloodfist or +min/+max jewels socketed in armor/helm/shield).
+min/+max damage charms.
What doesn't count towards Vengeance's elemental damage (though still applies to the weapon blow itself):
Off-weapon ED, from Strength, abilities such as Might Aura, %ED from armor such as Duress Rune Word, or armor-socketed +%ED jewels.
Weapon added damage that reads "damage + xx" such as Grief Rune Word and The Redeemer. This has been tested in game to not work.
Factors such as Deadly Strike, Open Wounds or Crushing Blow.