For three mana you can call in another Knight (also with vigilance, notably), and for one mana you can tap some of your other Knights to remove a threat on the board
It was ubiquitous in all formats in any deck that could run it
On the one hand, I think its good, it has nice stats, and being able to give it first strike is pretty nice

First, let's check out the original list: Coven Counters | Commander | Wizards of the Coast Commander (1) 1 Leinore, Autumn Sovereign Creatures (38) 1 Abzan Falconer 1 Ainok Bond-Kin 1 Angel of Glory's Rise 1 Avacyn's Pilgrim 1 Bastion Protector 1 Champion of Lambholt 1 Custodi Soulbinders 1 Dawnhart Wardens 1 Dearly Departed 1 Elite Scaleguard 1 Enduring Scalelord 1 Eternal Witness 1 Gyre Sage 1 Herald of War 1 Heronblade Elite 1 Heron's Grace Champion 1 Juniper Order Ranger 1 Kessig Cagebreakers 1 Knight of the White Orchid 1 Kurbis, Harvest Celebrant 1 Kyler, Sigardian Emissary 1 Mikaeus, the Lunarch 1 Moorland Rescuer 1 Odric, Master Tactician 1 Orzhov Advokist 1 Riders of Gavony 1 Sigarda, Heron's Grace 1 Sigarda's Vanguard 1 Sigardian Zealot 1 Somberwald Beastmaster 1 Somberwald Sage 1 Stalwart Pathlighter 1 Trostani's Summoner 1 Verdurous Gearhulk 1 Victory's Envoy 1 Wall of Mourning 1 Wild Beastmaster 1 Yavimaya Elder Instants (6) 1 Beast Within 1 Inspiring Call 1 Return to Dust 1 Ruinous Intrusion 1 Swords to Plowshares 1 Unbreakable Formation Sorceries (8) 1 Bestial Menace 1 Biogenic Upgrade 1 Celebrate the Harvest 1 Celestial Judgment 1 Cleansing Nova 1 Growth Spasm 1 Hour of Reckoning 1 Shamanic Revelation Enchantments (4) 1 Citadel Siege 1 Curse of Clinging Webs 1 Curse of Conformity 1 Death's Presence Artifacts (6) 1 Arcane Signet 1 Lifecrafter's Bestiary 1 Moonsilver Key 1 Sol Ring 1 Swiftfoot Boots 1 Talisman of Unty Right out of the gate, I'll admit I'm kind of baffled by this list

Like most Magic: The Gathering cards, the value of Doubling Season depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (Commander Masters)
Differences between Extra-Spicy WW and regular spicy WW: Extra-Spicy guarantees a win from our higher-end binders, with 2XM toppers (Sword of Feast and Famine, Mana Crypt, Stoneforge Mystic, etc) and the more premier playable singles such as Fetchlands, Mana rocks, and special promotions being present alongside a plethora of our most popular staples