Database: superhero (difficulty: simple)
Question: What is the superpowers of the superhero has Alexander J. Mercer as their full name?
SQL: SELECT T3.power_name FROM superhero AS T1 INNER JOIN hero_power AS T2 ON T1.id = T2.hero_id INNER JOIN superpower AS T3 ON T2.power_id = T3.id WHERE T1.full_name = 'Alexander J. Mercer'