Key Sword Lock falls under the Key Sword, and it already has that ability.
Piercing Super Ki Blast is valid.
"God Meteor of Calamity" has nothing to do with Energy Absorption, I'm not quite sure what this would fall under wiki-wise but it's not Statistics Amplification Negation.
"Dark Demon God Heroes Rush" isn't summoning Chamel, it's summoning a Hero Avatar (who happens to look identical to Chamel) but it is indeed Summoning, as well as Statistics Stealing.
Super Attack Sealer Unit is not Power Mimicry, it prevents the enemy team from being able to use their Super Attacks for a round. Demigra also requires two allies to use it - though this isn't a problem for him as his mirages would qualify.
Dark Destroyer X isn't really amped Statistics Reduction but otherwise that's accurate.
Most of these would fall under Demigra's regular Heroes key, BM5-062 and BM6-061 are his only Universe Creation Saga cards there.
I'll wait a bit for any other feedback, though I don't expect there'll be any opposing views - there'll probably need to be a discussion on how exactly Power Level in Heroes should be treated in regards to God Meteor of Calamity.