If you reveal more than one Devourer of Destiny from your opening hand, you'll put that many triggered abilities on the stack at the beginning of your first upkeep
These will help you not lose
While incredibly luck-based, the immediate removal can disrupt many strategies (especially those that need to spend turns building Energy), and if you're lucky enough you can hit the Instant-Win Condition by leaving your opponent with no Pokmon on the field by shuffling them all back and them failing to find any additional Basic Pokmon
So basically you now have access to all of the incredible power present within Charizard ex, and now an attack thats even stronger and easier to navigate than Raging Bolt exs Bellowing Thunder
With 81% of submitted decks not running Mana Crypt, though, it's clear that not all decks need Crypt to function
Whereas Bosss Orders is a card that cant draw you cards in an otherwise dead hand, Serena can