I'm glad you asked
While you may think of activated abilities as something that cards on the battlefield use, like lands tapping for mana or planeswalkers using their abilities, theres actually no reason why we cant have abilities that activate from other zones
As for Zenos, the main antagonist of the Stormblood expansion is a double-faced creature card that allows the Garlean prince to transform into the legendary dragon Shinryu after taking down a chosen opponent
These can be hard to tell apart online, even if you know how to spot a fake Pokmon card - sometimes what you see is not what you get
Commander is one of Magic: The Gatherings most popular formats, so it makes sense that Foundations, a set meant to serve as a hopping-on point for the game, would be loaded with all sorts of cool new and returning Legendary Creatures
If it is successful, then box prices can remain elevated