Its basically just Nights Whisper, where one of the cards you draw is a Preordain you have to play that turn
Im not a huge fan of seeing too many cards that break the legend rule, but Spark Double is still a great card that has tons of appeal in Commander
Equip Back Summon: Alexander Enchantment Creature - Saga Construct (As this saga enters and after your draw step, add a lore counter
Cards like Tandem Lookout and Keen Sense allow you to draw cards when Niv-Mizzet deals damage, allowing you to draw more cards, then deal more damage, and then draw more cards until the opponent has no life
This is also where Marvel Snap comes into play, as, in defense of developer Second Dinner, regular retooling of new and old cards makes power creep less of an issue, but the cards themselves, well, they're pricey