Insanely useful in a bounce deck with cards like Faerie Impostor and a couple others that will be featured shortly, there's really nothing to say no to about a free creature that can even generate mana for you, since it allows you to untap any 2 land cards you control
Inalla, Archmage Ritualist Inalla, Archmage Ritualist Jeleva, Nephalia's Scourge Kefka, Court Mage Kefka, Ruler of Ruin Kess, Dissident Mage Mairsil, the Pretender Marchesa, the Black Rose Nekusar, the Mindrazer Obeka, Brute Chronologist Parnesse, the Subtle Brush Saruman, the White Hand
While Sidisi only costs two, you do need a creature other than it in play to do the thing, and that creature is from your yard
It's not Prismatic Evolutions