Assassinate

Jorbs

Because you're typically stuck on 3 energy per turn, the 0-cost Innate cards (Backstab and Assassinate) are quite appealing as a way to do something with Silent's 7-card starting hand. Being able to deal ~30 or so damage very quickly in a fight will help a lot in many of the Act 1 and Act 2 fights, where it'll let you kill one of the enemies, reducing the incoming damage from the enemies to something you can safely defend against.

Baalorlord

Basically a super-backstab. Very helpful against short hallway combats in Act 2 and 3 by letting you burst down one target quickly. If you need long-term power, consider a different rare card.