You cant blink Sephiroth to re-trigger the emblem, but cards like [[Agathas Soul Cauldron]] can let you stack triggers by giving his ability to others
They are a star of the set's Limited format, with plenty of strategies attached to them to allow for a range of powerful options
On the other hand, if you plan on building your own deck and strategy and just want some solid cards you can use in it, go with Amber/Emerald
Volrath, the Shapestealer Volrath, the Shapestealer can be a convenient removal source in -1/-1 counter decks, or it can simply be a versatile Clone card
Many creatures do considerably more complicated things, while most types of card are almost completely defined by their ability text
I fully expect the price on nonfoil uncommon FCAs to drop dramatically over time, rares and mythics will still be hard to pull but there will be a fair amount more of the nonfoils out there, thanks to the Play Boosters