Do multiple sources of Assault and Shield keywords stack/sum together?

Ruling: Yes, multiple sources of both Assault and Shield keywords sum together.

Sequence:

• If a unit has Assault (or has been granted Assault) and receives Assault from an additional source, sum all Assault values
• If a unit has Shield (or has been granted Shield) and receives Shield from an additional source, sum all Shield values

Nuances:

• This applies whether the keyword is inherent to the unit or granted by external sources
• All granted keyword values are summed, not just the highest value