Why don't you use the new zombie jewel that makes them always slam? It should make everything even faster

Strength stacking zombie builds ftw. Although my guys are just 4L and running cleanup/support for me (dual wield brutus sprinkler / mon'tegruls with primary skill molten strike).

I guess the Overflowing Chalice thing makes sense:  You are never under the "Effect of any Overflowing Chalice Flask", your zombies are, so its "Gains no Charges" clause never gets triggered (since you're the one who gains charges, not your zombies).

Supersonic Acrobatic Rocket-Powered Battle-Zombies! An Umbilicus Baron Zombie build.