There have been a lot of powerful hate cards against red Chill, Warmth, Sanctimony but I think CoP: Red was both the best and the most iconic
They are Vrondiss, Rage of Ancients (a Dragonborn Barbarian, leading the red/green Draconic Rage deck), Prosper, Tome-Bound (a Tiefling Warlock, helming the red/black Planar Portal deck), Sefris of the Hidden Ways (a Genasi Wizard, leading the White/Blue/Black Dungeons of Death deck), and, finally, Galea, Kindler of Hope (a Half-Elf Paladin, topping the White/Blue/Green Aura of Courage deck)
The first is that on your end step, you can give away a creature you control with two +1/+1 counters and then it's tapped and goaded for the game
Invasion of Ravnica is the only colorless battle
Reshiram is best used as a mid-game attacker who helps another attack, or as a late-game sweeper to take decisive knockouts