If the opponent Kaalia attacked is no longer in the game when its ability resolves, you may put an Angel, Demon, or Dragon creature card onto the battlefield tapped, but it won't be attacking anyone and it won't be an attacking creature
I also really appreciated the vertical art, which worked for many of the Summons we wanted to depict
If Valgavoth somehow enters the battlefield during an opponent's turn and that opponent had lost life earlier in the turn, its last ability won't trigger if that opponent loses life later in the turn
If you want to make the most money, sell your chase cards individually
Remember, that's any plains card, not just a basic Plains
Each new Commander could potentially increase demand for dozens of old cards, some which could see significant price spikes