Patch notes I don't understand, can someone clarify this for me?

patch note.gif

What cities are we talking about exactly? Are these the ones during a fight, or the ones acquired by a guild?

Does this mean that if a guild holds 11 city buffs for instance, their enemies get (11-2)x10% as a buff? (90%)

Or does this mean that when the fight begins and the defender starts in B, attacker gets 20% buff?