Nemesis quake cannon

"When not attacking Titans, Knights or Super-heavies, a weapon with this Special Rule must make Snap Shots."
If the target of a Shooting Attack is not a Unit entirely compassed of Models with the Titan, Knight, or Super-heavy Sub-Type or other Models with a Base Wounds Characteristic of 10 or more, then all attacks made for a Weapon with this Special Rule must be made as Snap Shots.

"A Weapon with this Special Rule makes other Weapons attack as Snap Shots when used."
If a Weapon with this Special Rule is used as part of a Model's Shooting Attack, then all other Weapons used in that or any other Shooting Attack made by that Model in the same Phase, must attack as Snap Shots. If other Shooting Attacks have already been made in the same Phase by a Model with a Weapon that has this Special Rule and those attacks were not made as Snap Shots, then a Weapon with this Special Rule may not be fired in the same Shooting Phase. Furthermore, a Weapon with this Special Rule may not be used to attack as part of any Shooting Attack made as part of any Reaction.

"Attacks made with the Blast (X) Special Rule use a Blast Marker to determine how many Hits are caused."
When making attacks with a Weapon that has the Blast (X) Special Rule, before any Hit Tests are made, a Blast Marker must first be placed to determine how many Hits may be inflicted by the attack. The Player making the attack must place the Blast Marker indicated in brackets as part of the Special Rule so that the hole in the middle is entirely over the base of any one model in the Target Unit. Once the blast Marker has been placed, the Player making the attack must make a Hit Test for the attack, and each Model from the Target Unit that is fully or partially under the Blast Marker will suffer 1 Hit if the Hit Test is successful.

*Hits on Other Units*
If any Models form Units other than the Target Unit are fully or partially covered by the Blast Marker, then a new Fire Group must be created for those Hits and set to one side. Continue resolving the Shooting Attack on the original Target Unit, and once that Shooting Attack has been completely resolved begin a new Shooting Attack to resolve those additional Fire Groups generated for Units other than the original Target Unit.

If the Hit Test is unsuccessful then no Hits are inflicted and the Player making the attack must make a Scatter Roll for the Blast Marker (see the Rules for Scatter in the Warhammer: The Horus Heresy - Age of Darkness Rulebook). Once a Scatter Roll has been made for the Blast Marker and it has been moved, one Hit is inflicted on a Unit for each Model from that Unit that is wholly or partially covered by the Blast Marker.