2 2000 World Challenge Super Secret Battle National w/ Winners Face No
Occasionally, you may have to play the Guzma and Hala simply to find a Float Stone to retreat (if you already have ADP and Double Dragon Energy) if this is the case, you should certainly do so, as the guarantee is more valuable than any additional resources you might get by being risky and playing, say, a Professor Juniper instead
Even better, there aren't any seller fees associated with sales
Getting an army of tokens in addition to ramp in a color famous for lacking in that department makes this legendary artifact a powerful inclusion to many white decks
On summon, it can add an illusion monster from your deck to your hand making it an excellent searcher for the archetype
They also have population reports which tell you how many cards have achieved a particular grade (example here)