Once you have completed:
Level 15 “Darkseid’s Palace”
You will come across 2 more new characters to battle against and their varied abilities, nothing too technical or confusing to worry about.
Then after a cinematic pop, pop achievement unlocked.
Also your 100g
for completing the story!!
Some players have stated the achievement isn’t popping, try resetting your Xbox (hard reset) load in and out of your game and tag.