Gordius Wheel

Strictly speaking, the Noble Phantasm is the Gordius Wheel (ゴルディアス・ホイール), Wheel of Heaven's Authority (神威の車輪); just like what Enuma Elish is to Ea, Via Expugnatio is the trampling attack performed with the Gordius Wheel.

The damage is decided by two rolls, for the hooves of the divine bulls and the wheels of the chariot. Along with all physical damage, there also is the effects of lightnings, the manifestation of Zeus. Should the target fail its STR check, additional damage will be dealt.

Source: status page of Fate/Zero #3.