While Swallowed by Leviathan is a three-cost card, its the kind of thing that can really irritate a rival in the late-game once Commander tax is totting up and each piece of mana becomes more important
Bennie has you covered with Leonardo, the Balance and Splinter, the Mentor partnered up
Losing control of Locke after the last ability has triggered won't affect your ability to cast a spell from among the milled cards
Each one has a strong questing value that forces opponents to challenge or risk falling behind, and then once challenged and/or banished, their effects activate drawing you cards, forcing opponents to discard or return a character to their hand, and more
There are higher levels of competition now The first set championships came at a unique time just before the real competitive level of play started (those being Lorcana Challenges)
This would represent her speed in-game and serve as a fun nod to Lightning (bolt). It may not seem very powerful, but perhaps she can be flickered or has an ability to flicker herself