Normally, evoking Solitude, Fury, or Endurance would leave you down a card in the exchange, but Risen Reef does a solid job at keeping you at parity when casting them for free
In a multiverse, anything is possible
Tucking something on ETB is incredibly strong, especially in the blink colors of blue and white, and doing it to each opponent is going to be at least passably good in EDH
A 0 loyalty ability that draws you a card is going to be nice if youre ahead, and if youre behind you can use her -3, and because her Spider friends have Reach, it is going to be difficult for your opponent to go after Lolth very effectively
Regardless of how playable it is, I'm expecting plenty of fans to be clamoring for this card - especially the nifty extended art variant below