Silence PB gives a range 2, 6 fpa smite, +2 skills, 75% all resists and 20% FHR.
Silence Zerker gives range 3, 8 fpa smite (need 35% IAS to reach 6 fpa), and others.

Scourge can also be good, because it has range 3, and with a -10 base speed. 35% IAS for 6 fpa, 10 (or 6..) % for 7 fpa.

That's assuming you have a lv 20 Fana aura on.

If you are only going to smite, you won't need Ohm. Ber and Um it as you see fit, depend on if you want CB or Open Wound. CB doesn't work that well with low HP opponents though.