Many players think about mana efficiency with respect to other types of cards (particularly creatures) but do not really consider it when it comes to card-drawing
a detective, and he investigates
Id also like to highlight that Containment Priest is a criminally underplayed card that stops a variety of things that youre likely to see in Commander
Being able to steal your opponents spells is always good, and it opens up the possibility to cast basically anything you steal since you can play them by paying life instead of mana
Lightning Bolt Chaos Warp Vandalblast Electrodominance Abrade Shatterskull Smashing (Shatterskull, the Hammer Pass, it's a flip card) By Force Mizzium Mortars Wild Magic Surge Red Elemental Blast / Pyroblast Fiery Confluence Comet Storm -- Fireball Cast into the Fire Flametongue Kavu Board Wipes Red is also great at dealing lots of damage to everything on the board
Heliod, Sun-Crowned Heliod, Sun-Crowned is powerful because its very flexible: It's among the best mono-white commanders in the game, but it's also a role-player in any given deck