According to Magic's Head Designer Mark Rosewater, this time they were also looking for some mechanical overlap with Jeskai, since Temur and Jeskai share two of their three colors
Its a standalone in which the TARDIS consciousness (yeah, its sentient) is trapped in a mortal vessel
I particularly love Ecto-1 because you could very easily combine it with a card that throws a few creatures into your graveyard and create feedback loop that makes a massive monster you can wipe out your opponents with
Many abilities of plane cards affect all players, while many others affect only the planar controller, so read each ability carefully
And yes, technically you can spend your hard-earned gold buying those , but why buy packs when you can get them for free
Sazhs Chocobo ended up getting its own card, and it fits as the perfect one-drop on the Chocobo curve, scaling in size as the game progresses