Kalista'sbond effect originates from Kalista, if her bond target gets 2Purified, it will maintain the bond with Kalista. Hence Purify Kalista, not the bonded target.
Killing Kalista with Chronicler of Ruin will not make the requirement to level up be 1/3. Don't try that.
Text becomes: "Each round, the first time I attack revive an attacking Ephemeral copy of the Strongest dead allied follower. This round, we're bonded and it takes damage for me."
Old Text: "The first time I attack each round, revive an attacking Ephemeral copy of the Strongest dead allied follower. This round, we're bonded and it takes damage for me."
Flavor becomes: "The wronged shall have their vengeance!"
Old Flavor: "In life, she was a general, a protector, a hero. But as flesh gave way, she was left with naught but the blazing fires of retribution--an undying spirit of vengeance."
Text becomes: "The first time I attack each round, revive an attacking Ephemeral copy of the Strongest dead allied follower. This round, we're bonded and it takes damage for me."
Old Text: "Play: Bond with an ally. Grant it +2|+0 while we are bonded. Attack: Revive that ally attacking and reforge our bond."
Text becomes: "Play: Bond with an ally. Grant it +2|+0 while we are bonded. Attack: Revive that ally attacking and reforge our bond." (Keyword is highlighted.)
Old Text: "Play: Bond with an ally. Grant it +2|+0 while we are bonded. Attack: Revive that ally attacking and reforge our bond."