Olivia is actually the Queen of Control Finishers. When she's in play, she functions much like a planeswalker: remove her, or die. In particular, she eats small aggro creatures for breakfast, and dominates the creature-based matchups. She routinely took over so many games here that I'm currently benching her for the time being, to give other cards some room to breathe.
It's funny, because while I don't run many monocolour sevens, I find that expensive multicolour drops are actually not that difficult to splash and include. While it's sometimes tough to justify running good, cheap,
two-color aggro creatures, because you aren't guaranteed to cast them on curve, it's not hard to assemble all of your splash colours by the time you hit your seventh land drop. This has let a variety of big
multicolour creatures shine here. I wouldn't be so quick to dismiss them without giving them a shot.
Of course, with all that said,
Sphinx's Revelation is objectively the more powerful card. The only reason I don't have one is that I'm waiting for its $25 price tag to dip. I'm just wondering if it's at all plausible to run both of these cards in a UW section, which is always a popular colour combination, but surprisingly doesn't have many interesting gold cards.