Magic: the Gathering in the UK
I don't like lacerator all that much. You really need to be heavy 1-2 drops, with a curve pretty much topping out at 3 to make him viable. In a deck with 3 one drops and 4 2 drops I just don't think he's good enough. If you play him on turn 1 then great, but anything past that he's just a bear with a drawback and if you're not getting in for the heavy beats, that drawback is enough to avoid him.
It depends how aggro Kieran's build was, I think there are arguments for both picks.
I went 3-0 in that draft in the end and the Scorpion was one of the MVPs. When he comes down on turn 3 your opponent pretty much has to stop attacking. Even if you're playing an aggressive deck, so is everyone else, and interfering with their plans seems better than getting just another attacker. Plus Lacerator can only be played in heavy black decks, whilst Scorpion could be taken by a player to the left(as its the first pack) who might then cut me out of black on the way back having opted for it as a secondary colour based on getting such a good creature so late. By taking the more splashable card I help cut black more heavily and set myself up for a better second pack.