Once an Entity has started a Ritual, they are preoccupied with it until it is finished or turned into a Project. If they perform another Action or suffer any Damage while maintaining a Ritual, they must perform a Multitasking Save or Fail the Ritual.
A Multitasking Save is a Will Save. However, it gains any other Bonuses or Penalties that an Entity may have to Multitasking, as Appropriate.
If an Entity performs an Action while maintaining a Ritual, the Difficulty of the Multitasking Save is 15. If the Action is unusually complex or simple, the GM may increase or lower the Difficulty. They may also impose Properties, as Appropriate.
However, if an Entity suffers Damage, the Difficulty of the Multitasking Save varies. If they suffer enough Damage that some remains after Mitigation, they must perform a Multitasking Save after the Damage is resolved. The Difficulty of this Save is equal to 10 + the Unmitigated Damage. If all of the Damage is Mitigated, they are not required to perform a Multitasking Save.
Example: Johnny Tutorial is performing the Set Up - 80 Ritual on his favourite Heavy Sniper Rifle. He receives 15 Meat Damage from enemy fire. He has 4 Armour, Mitigating 4 of the 15 Meat Damage, leaving 11 Unmitigated. To maintain the Set Up Ritual, he must Successfully perform a Difficulty 21 Multitasking Save to avoid Failing the Ritual.