Caduceus, Staff of Hermes

If the equipped creature is dealt damage at the same time that you gain life (most likely because it dealt combat damage to a creature blocking or blocked by it) and your life total becomes 30 or greater as a result, the damage won’t be prevented. However, the equipped creature will have indestructible before state-based actions are checked, so it won’t be destroyed even if that damage would ordinarily be lethal.