The flexibility is great, but holding four mana up for interaction is admittedly easier at more casual tables, which probably accounts for why this card doesnt show up very often
See a complete list of the Additions and Subtractions from Fourth to Fifth Editions
At a very manageable converted mana cost of two generic and one white, it's easy to repeatedly play Lae'zel onto the battlefield, even if she is answered with removal
Here are two examples of potential mechanics we considered for heroes
This printing of the card was its first since it debuted in the Tempest set in 1997, so the novelty factor of that plus the supreme scarcity of From the Vault cards means this cards price point hovers above $100
It's solid on rate alone, and then the boast ability is both perfect for what black, Orzhov, or Jund decks want to be doing, and strapped to a flyer so you actually have an extremely good chance of being able to activate it more than once