In the 100th Century, in the planet Almeer-5, Melissa Trask was an idealistic electronics engineer who saw the corruption than existed under the rule of Nevlor. Wanted to fight against that in some way, she built a powerful armour, becoming herself in Metallica, but even with that powerful tool in her hands, she could n’t do much against the sheer number of Protectors, the robotic soldiers of the tyrant Nevlor. She ended along other fighters like Ava, Behemoth and Ultra-Man, as prisioners on the Nevlor’s dungeons.
Nevlor then employed impostors to take the heroes’ places. But with the help of XS, a speedster from the 30th century who was lost in the timestream, the heroes escaped and Metallica could take nback her armour and together defeated the impostors. After defeating their doppelgangers, Metallica took his friends to her secret lair, where Ava helped XS to return her to the time stream with the Spear of Destiny. The freed heroes had decided than created a new Legion of Super-heroes in the 100th century to take down the tyrany of Nevlor.