Can Janna heal my Sand Soldiers if they were targeted with Falling Star?

Card Information

• Janna, Savior: A Unit with the [Reaction] keyword. Her ability text is: "When you play me, heal your units here, then move up to one enemy unit from here to its base."
• Falling Star: A Spell that reads: "Deal 3 to a unit. Deal 3 to a unit. (You can choose different units.)"
• Sand Soldier: A token unit.

Ruling on Healing

According to Rule 405.1, Healing is the act of clearing damage from units. Healing only removes marked damage; it does not prevent damage from being dealt.

If your units are targeted by Falling Star, they will take the damage when the spell resolves. Because Janna, Savior has the [Reaction] keyword, she can be played during a Closed State (such as when a spell is on the chain).

Interaction Sequence

If you play Janna, Savior in response to Falling Star:

1. Falling Star is on the chain.
2. You play Janna, Savior as a [Reaction]. Because she has the [Reaction] keyword, she can be played while the chain is closed.
3. Janna, Savior enters the battlefield. Her "When you play me" triggered ability goes on the chain on top of Falling Star.
4. The chain resolves in LIFO (Last-In, First-Out) order:
   • Janna's ability resolves first: She heals your units at that battlefield.
   • Falling Star resolves second: It deals 3 damage to the targeted units.

Important Note: Because Falling Star resolves after Janna's ability, any damage she heals will be immediately reapplied if the units are hit by the spell. Janna cannot "save" a unit from dying to Falling Star if the damage from the spell is lethal, as the healing happens before the damage is dealt.

Note: I could not fully verify this ruling against the retrieved rules.