The downside would be a lot of these either cost a lot of mana or require a lot of build around, or both
In fact theres a subset of mechanics that can be read as this can be cast with another cost and produces a different effect, like split cards, evoke, etc
TL;DR Direct answer : The best Sapphire cards from Fabled to prioritize are Hades - Infernal Schemer, Aurora - Dreaming Guardian, Dig a Little Deeper, Mulan - Considerate Diplomat, and Cruella De Vil - Style Icon
As you may have noticed, the 'Staff' stamp present in the corner of this card and the Tapu Fini indicate that you can only get this card if you're a staff member at a designated event
This high efficiency has made Sabrina a staple in Pokmon TCG Pocket, an absolutely essential card like other already essential cards like Pok Ball and Professors Research