A 6/6 flyer is already a threat, but the moment it hits a player, it can wipe their entire creature board and clear the way for your next attacks
The bottom line is that you wont want all your card draw in only one of the colors in a typical multicolor EDH deck, so finding a few red draw staples helps make your decks more consistent
From there, you can stack the triggers and put Lumbering Battlement re-exiling Restoration Angel on top of Restoration Angel exiling Lumbering Battlement
Wrenn and Seven is an exceptional ramp tool, scooping up land cards from your deck and then placing them directly on the field
Sleeves are first and foremost the protection for your cards
Teferis Moat is one such example where the reference is quite clear, although it puts a different spin on things by caring about the color of creatures that want to attack you