21 cards where the text includes “proliferate” and the mana value <= 3 and the rarity is equal to common

Adaptive Sporesinger (Phyrexia: All Will Be One #157)
Blightbelly Rat (Phyrexia: All Will Be One #85)
Carnival Elephant Meteor (Unfinity Sticker Sheets #7)
Carnivorous Canopy (Phyrexia: All Will Be One #162)
Contagious Vorrac (Phyrexia: All Will Be One #164)
Contentious Plan (War of the Spark #46)
Copper Longlegs (Phyrexia: All Will Be One #165)
Courage in Crisis (Commander Masters #278)
Experimental Augury (Phyrexia: All Will Be One #49)
Grim Affliction (Modern Masters 2015 #84)
Guildpact Informant (War of the Spark #271)
Martyr for the Cause (War of the Spark #23)
Mesmerizing Dose (Phyrexia: All Will Be One #62)
Pollenbright Druid (Commander Masters #312)
Smell Fear (Modern Horizons 2 #173)
Steady Progress (Modern Masters 2015 #58)
Thirsting Roots (Phyrexia: All Will Be One #185)
Thrummingbird (Modern Masters 2015 #65)
Unbounded Potential (Commander Masters #67)
Volt Charge (Phyrexia: All Will Be One #155)
Whisper of the Dross (Phyrexia: All Will Be One #117)

Though this query has ended, its relics still slumber in New Argive.