The choices are: Inna's Temperance, Lacuni Prowlers, Tyrael's Might, Boots, Compass Rose
The most common combination is Inna's Temperance + Natalya's Bloody Footprints, but the choice is up to you. Top geared players use even Lacuni Prowlers, making it 3 MS items, but the reason is that those items provide highest dps (considering set bonus from Nat's).
Most people were three (Nat boots, Inna's pants, Lacuni) because these are BiS. But two (24%, just 1% short of the cap) are enough if you have pants or bracers that are better than affordable Inna's/Lacuni's for now.