Be glad you’ve missed the whole thing, mate. i and many others have only missed the good part and joined in on the bad part...
See? once the devs noticed that they have rolled out a brainless event (they call it a “bug”), they have simply made the sacrifice button disappear for the my team menu, but you could just go to the EVENT tab and click on GO and you were in sacrifice. sadly the event rewards and alchemist shards were missing at that point, so we got DOUBLE screwed up!
The devs don’t even acknowledge that and just ignore it. i have sacrificed a few months old collection of maxed chars and didn’t get any rewards...