Having access to red cards also means you get access to red removal and red card draw effects, which can help to churn through your deck for the answers you need
Cards like [c]Imperial Seal[/c] and [c]Demonic Tutor[/c] are typical examples
Master Duel banlist Check yourself before you deck yourself
Gallery and List of Buyback Cards Allay Anoint Blast from the Past Brush with Death Capsize Change of Heart Clockspinning Constant Mists Corpse Dance Demonic Collusion Disturbed Burial Elvish Fury Evangelize Evincar's Justice Fanning the Flames Flowstone Flood Forbid Haze of Rage Imps' Taunt Innocuous Insect Invulnerability Lab Rats Mind Games Mind Peel Mystic Speculation Pegasus Stampede Reaping the Rewards Recruit the Worthy Reiterate Searing Touch Seething Anger Shattering Pulse Slaughter Spell Burst Sprout Swarm Verdant Touch Walk the Aeons Whim of Volrath Whispers of the Muse Worthy Cause Wurmcalling Best Buyback cards Reiterate Much like Fork, Reiterate allows you to copy an instant or sorcery, but now you can do it every turn thanks to buyback

If your deck's key engine is a 4cmc commander like Kaalia of the Vast, for example, then you will want to run ramp cards that can get her out faster, which means ramp that is between 0-2cmc so you can cast Kaalia on turn 3 or earlier instead of her usual turn 4
It would rate around the middle of this list, if the cards weren't about to rotate out of Core constructed