Avada Kedavra, Voldemort's Iconic killing curse and the most potent of the Three Forbidden Curses, is undisputedly the best offensive magic in It can obliterate enemies and even bosses with massive health bars in one shot.

Source: https://gamerant.com/hogwarts-legacy-best-dark-arts-spells/

It ended with Voldemort casting the killing curse, Avada Kedavra, and killing Harry.

Source: https://www.cbr.com/harry-potter-horcrux-order-destroyed-hogwarts/

Just like in the source material, Avada Kedavra is an instant-kill attack, which is naturally going to be an immensely powerful tool in your spellbook.

Source: https://www.digitaltrends.com/gaming/hogwarts-legacy-learn-avada-kedavra/

Therefore, it is only with great severity that Avada Kedavra is ever seen or heard, unless a truly horrendous individual is the one wielding it.

Source: https://gamerant.com/hogwarts-legacy-avada-kedavra-powerful-no-nerf-good/

This was best shown through the three Unforgivable Curses: Avada Kedavra, Crucio and Imperio, which kill, torture and control, respectively.

Source: https://www.cbr.com/voldemort-cruciatus-curse-worse-avada-kedavra/

What Does Avada Kedavra Actually Mean in Harry Potter?

Source: https://www.cbr.com/what-avada-kedavra-mean-harry-potter/