Legendary Creature — Human Shaman // Legendary Planeswalker — Chandra
Legendary Creature — Human Shaman
Whenever you cast a red spell, untap Chandra.
{T}: Chandra deals 1 damage to target player or planeswalker. If Chandra has dealt 3 or more damage this turn, exile her, then return her to the battlefield transformed under her owner's control.
Legendary Planeswalker — Chandra
+1: Chandra deals 2 damage to target player or planeswalker.
−2: Chandra deals 2 damage to target creature.
−7: Chandra deals 6 damage to each opponent. Each player dealt damage this way gets an emblem with "At the beginning of your upkeep, this emblem deals 3 damage to you."
This triggers when the spell is cast, before it resolves. Even if the spell is countered, the cast trigger still resolves. Copies of spells are not cast, so they won't trigger this.