Well, I believe the answer is actually supposed to be that you would choose the order of activation, because they do both happen at the same time (opponent has drawn and blocked at the exact same moment, triggering them both). However, there is no explicit rule that says that when multiple actions taken by one player simultaneously (which these are), the user gets to choose the order, but we know that to be the case due to how we ruled that SoG+NJ, when it mattered with the old SoG, could rescue Thorns and the Shuffler in whatever order the player using the doms desired and shuffle souls if they wanted.
On the flip side, the standard rule has been that the 'first on the table' is active first, though that is
also not an explicit rule that I can find, and so I cannot tell you if that is supposed to only refer to when more than one players' abilities are activating.
So on that note, can we get some definitions for what happens with simultaneous abilities so that they can be added to the rules?
(Unless I'm just missing something and someone can post the rules for reference and make me look silly)
