Ok well... It DOES "Technically" fall into the realm of "doable by most groups of 95"...

I still think it's a bit much. It would be acceptable if you could get the Umbral Marrow from any Arch Dynamis Boss.

How about this:

Bastok/Sandy/Windurst Dynamis: Arch Dynamis Stone = 25% Chance at Umbral Marrow.
Valkrum/Bubu/Qufim Dynamis: Arch Marlboro/Dragon/Gigas = 33% Chance at Umbral Marrow.
Beacedine Dynamis: Arch Angra Manyu = 50% Chance at Umbral Marrow.
Xarcabard/Tavnazia Dynamis: Arch Dynamis Lord/Diablos(DSCH) = 100% Chance at Umbral Marrow.

And:
Dynamis Lord/Diablos(nq) = 5% chance.
Angra Manyu = 3% Chance.
Any City "Boss" Stone = 1% Chance

Can you put in that request?