Plus, you always tutor for the same slate of cards, that perfect set of Esper enchantments for gross card drawing, breaking Zur, and more is always the same because the subset of quality, on-color 3 mana or fewer options is relatively small
Rhoda, Geist Avenger + Timin, Youthful Geist I applaud Wizards for expanding the design space around tapper effects in blue and white, but they're often just not strong enough to justify an entire deck themed around them
Any exerted character can be challenged (attacked) and banished from play (sent to the discard pile)
For triggered abilities, the key words to look for are At, When, or Whenever
Not competitively, but I can see myself building a deck around Rubinia Soulsinger if I pull one in a dollar pack at my LGS