A "sacrificial act" refers to a selfless action someone takes where they give up something important or valuable for the benefit of others or a greater cause. Full definition
Listening is one of the most sacrificial acts a person can do because it demands energy, attention and love. (relevantmagazine.com)
These two characters represent the mixture of evil and good in human beings but also, in their love for Lyra and their sacrificial acts, a powerful symbol of redemption and transformation in the face of evil. (religion-online.org)
These sacrificial acts provided order and sanity, and ultimately civilized untamed parts of America. (firstthings.com)