Chandra, Fire of Kaladesh // Chandra, Roaring Flame

The design question was always how to make a planeswalker you have to earn. Front-side Chandra is a creature, not a walker: a 2/2 that pings for one and untaps every time you cast a red spell, meaning a burn-heavy turn can fire her ability multiple times. Cross the three-damage-per-turn threshold and she flips, arriving as a full planeswalker with her normal starting loyalty. This is the flip-walker template that a handful of legendary creatures in this era used to gate their walker forms behind a play pattern rather than a mana cost, and Chandra's gate is the most aggressive of them: she wants a deck already committed to throwing damage, then pays off that commitment by graduating into a card that keeps throwing it. The back half is orthodox Chandra (a plus that reaches the face, a minus that deals 2 to a creature, an ultimate that hands out damage-over-time emblems), but the interesting part is the transition. The front side is fragile and slow if your deck can't feed it red spells; a three-mana 2/2 that needs a full turn of tapping to convert is a genuine liability against decks that clock faster than you assemble your flip. That fragility is the price. What you buy for it is a threat that starts as removable-by-creature-combat and ends as a planeswalker that no creature can simply block or trade with, all without ever paying planeswalker mana.