Once you have completed:
Level 11
”Apokolips, Wow”*** Spoiler - click to reveal ***This level is very short compared to the rest of the other levels, and half of it is aboard a large shooting tank shooting golden cannon with [cn_] and Silver missiles with 
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As soon as you reach the end of the long bridge as you hit the end and nearly run over an enemy you drop a key, and jump into the end of the levels cinematic
Then that magic pop achievement unlocked.
Congratulations!
Happy Hunting