The second will be opened and the same process will occur although they will be passed on to the right
Looking at my cube, there is critical mass for: Goblins (R) Humans (all) Warriors (WBR) And, with some effort, other tribes could get critical mass running only cards that are cubeable by themselves, keeping the Poison effect to a minimum: Soldiers (W) Wizards (U) Shamans (RG) Vampires (B) I'm fine with dedicating 2-3 slots per color so each of these tribes have a Lord or some other linear effect as a nod to play them (Goblin Chieftain, Champion of the Parish, Chief of the Edge) but I don't want this cube to be mainly tribal, just have an extra layer of synergy that cares about the creature type line at a low opportunity cost
Fill Your Graveyard, Then Empty It Every time your Orc Army (or any other Army you control) deals combat damage to an opponent, Sauron, the Dark Lord, gives you the option to discard you hand and draw four more cards
If not, should they be swapped