Deck builders tried Solitude in nearly every deck that could support it, and it eventually found homes Azorius Control, Four-Color Blink, and Elementals
4 loyalty Player 2 - During his or her upkeep, Player 1 uses Teferi, Master of Time to use its first ability to +1 and Loot
The result is a deck that feels cohesive, with every spell or permanent working toward the same game plan
Generally you can transform a card if you can meet the condition to transform it
Even in Legacy, where Black Lotus is banned, the card could still abuse Lions Eye Diamond and, even though you have to discard your hand to get the mana, Will lets you replay those cards anyway
Shanid obviously requires you to be playing a lot of legendary permanents, and luckily, many knights are legendary