Mantis is an agent of Darkseid and apparently related to the bugs of New
Genesis. He preceded Darkseid in travelling to Eearthm, in the hopes of wreaking
a little havoc for his master's imminent arrival. But the Forever People,
summoning the Infinity Man, defeated him.
Later he assembled many of New Genesis' bugs to form an army and invade
Earth, but the combined efforts of Orion, Forager and Lightray sent them
retreating away from Earth. Some years later, Mantis, on behalf of Darkseid, and
perhaps with a little self-motivation, destroyed the bug colony in a giant
blast: Orion responded by virtually slaughtering him. But Mantis has recently
returned to action, proving Darkseid's great powers.
Mantis has a deadly touch; he can either burn or freeze something with it.
He also has the ability, perhaps a power given to him by Darkseid, to create
anti-matter within an object; when matter and anti-matter make contact, it makes
for an extraordinary explosion.