draw cards equal to power mtg Prime Speaker Zegana [Gatecrash] mtg cards like greater good

Shields of Velis Vel is a sweet little enabler for tribal decks, particularly Sylvia and Khorvath

You can activate Arcum for Sewer Cam, untap him, Arcum for Repurposing Bay, sac the Cam to get Corridor Monitor, untap Arcum and hold priority to sac the Monitor for Encroaching Mycosynth, and now you can even sac Arcum to himself to get Mind Over Matter, and use Repurposing Bay to get The One Ring, and now you can fire off the MoM + TOR combo you mention

I know Ive concentrated on the second ability, but it really is that good

You are far more likely to run into situations where any random on-color card generated from Gatherer's random card button is going to be better