Place eggs in a saucepan and cover with water. Boil for 10 minutes, then transfer eggs to a bowl of warm water. Allow eggs to rest in the warm water for 10 more minutes.
Peel and rinse eggs under cold water to cool; cube eggs.
Mash eggs, avocado, celery, and mustard in a bowl with a fork until well mixed but still chunky. Season with salt, black pepper, and garlic powder.
