There are some changes to the numbering and set labels for cards from when the original D23 promo set was shown through to the first mass-produced set
Love it or hate it, and politics aside, there are some awesome cards that grace the list
It ETBs with energy, sure, but it can convert energy to creatures without tapping, which, of course, means you can generate infinite tokens pretty easily with the other cards here
Hitting the field on turn 2 and flipping the following turn gives you the potential to explode if you draw into the right burn spells
If your infect deck is doing its thing, you wont need more than two hits from this black skeleton dragon to end the game, and it gets better with power pumping effects or double strike (Fireshrieker)