Looks solid to me! Seems like a textbook quality tie-in with a great hook that contributes to the story.
This is H-E-D's event and the rules were laid out earlier here. Aside from Moonstone and Carnage, H-E-D has chosen to make the characters he reserved available for general use during the event. So there should be no problem using most of the Redeemers that he listed (I probably wouldn't kill them off, though, without asking H-E-D first). He's also said that you can add Redeemers of your choosing as well.
I'm going to be doing some tie-ins myself that I'll announce soon!