Does a stunned unit deal damage back when targeted by Carnivorous Snapvine's summon effect or Challenge spell?

Ruling: Yes, a stunned unit still deals damage back when targeted by Carnivorous Snapvine's summon effect or Challenge spell. Stun only prevents a unit from contributing its might to damage in combat, not damage dealt through abilities and spells.

Nuances:

• Stun specifically affects combat damage only
• Damage dealt through card abilities and spells is not affected by stun status