Whenever a player casts an instant or sorcery spell, you draw a card

A Little Chat Abigale, Poet Laureate Aboleth Spawn Absorbing Man Abyssal Harvester Activated Sleeper Adagia, Windswept Bastion Adventurous Eater Aethertow Agate Instigator Agrus Kos, Eternal Soldier Altar Ibn-La'Ahad Altered Ego Amphibian Downpour Amphin Mutineer Angel of Indemnity Angel of Sanctions Anhelo, the Painter Anikthea, Hand of Erebos Anointer Priest Applied Geometry Araumi of the Dead Tide Arboreal Alliance Arcane Artisan Arcane Heist Arcane Proxy Arcane Savant Ardyn, the Usurper Arna Kennerd, Skycaptain Artisan of Forms Ashad, the Lone Cyberman Ashling's Command Ashling, Flame Dancer Ashnod the Uncaring Assemble from Parts Assembly Hall Assimilation Aegis Astral Steel Audacious Swap Aurora Shifter Auton Soldier Aven Wind Guide Back from the Brink Banish into Fable Banshee of the Dread Choir Barkshell Blessing Baron Helmut Zemo Barroom Brawl Battle for Bretagard Battlemage's Bracers Beamsplitter Mage Belonging Benthic Anomaly Bifurcate Biowaste Blob Blade of Selves Blade of Shared Souls Blazing Firesinger Bloodforged Battle-Axe Bloodthirsty Adversary Blue Mage's Cane Blue Ribbon Blue Sun's Twilight Body Double Bramble Sovereign Brass Knuckles Brenard, Ginger Sculptor Briarblade Adept Brigid's Command Broodbirth Viper Brudiclad, Telchor Engineer Burn Trail

Sacrifice Your Lands Instead of playing lands and tapping them for mana, you sacrifice lands to generate mana (and the sacrificed lands go from the top row to the graveyard)
It levels the playing field for aggro in Commander by damaging all your opponents at once, which makes it far easier for aggro and Voltron decks to close the game
In any color, that rate would be outrageous, but in Red, it's nothing short of a fortune