At just $0.50, Dragon Arch is a no-brainer when it comes to speeding up Painbow, and dealing more damage as a result
To maximize this impactful ability in Commander, you want to fill your deck with as many 2-colored permanents as possible
Midnight Reaper A key card draw engine for Teysa Karlov style aristocrats decks as well as Wilhelt, the Rotcleaver zombie decks, there are only so many cards that do what Midnight Reaper does, so this is a must have for a ton of black decks
It gives your commanders Protection from everything at instant speed
Lifegain is the natural antithesis of burn, and cards like Sunspine Lynx or Sulfuric Vortex ensure life totals can only decrease
Normal Magic decks will naturally create inefficient moments where you spend a three-damage spell on a one-toughness creature, so you need to force energy decks to deal with some occasional inefficiency by design