The 18+ bust is due to release in the UK and Europe on May 1, but it will ship for US fans from April 11 when buying through the official online store. The LEGO Group rarely (if ever) offers pre-orders on products, so it’ll be interesting to see whether this sets a precedent for future sets.
There’s a limit of two copies of 76199 Carnage per customer, but the ability to add it to your bag means that buying even one will contribute towards the $100 threshold to qualify for 40450 Amelia Earhart Tribute.
You’ll still need to top up your order to reach that minimum spend if you’re only after a single Carnage bust, as the 546-piece set retails for $59.99. But if you’re somehow short on sets to buy at the moment (despite dozens of new sets launching on March 1), it’s another option for getting you at least some way towards the current gift-with-purchase.