When you do get the effect off, its a gamble: itll mill cards from your opponent until they reveal a land, and the equipped creature gains +1/+0 per card revealed
This won't touch generic mana costs or other colors, and it only works on permanents, which was clearly done to keep them from getting broken by casting free Brainstorms, counters, Lightning Bolts, Swords to Plowshares, etc
Heres the most impactful reasons to play an ally strategy
Adrestia Adventurer's Airship Aerial Surveyor Aethersphere Harvester Aetherwing, Golden-Scale Flagship Air Response Unit Apocalypse Runner Aradara Express Arcee, Acrobatic Coupe Avengers Quinjet Balamb Garden, Airborne Ballista Charger Bespoke Battlewagon Bessie, the Doctor's Roadster Big Wheel Bladewheel Chariot Blitzwing, Adaptive Assailant Bomat Bazaar Barge Boommobile Boosted Sloop Broadcast Rambler Brotherhood Vertibird Brute Suit Burner Rocket Capenna Express Captain America's Motorcycle Careening Mine Cart Cargo Ship Carriage of Dreams Carrion Cruiser Clamorous Ironclad Cloudspire Skycycle Clown Car Colossal Plow Conqueror's Galleon Consulate Dreadnought Cryptcaller Chariot Cultivator's Caravan Cybership Cyclonus, Cybertronian Fighter Damocles Base, Sword of Kang Daredevil Dragster Debris Beetle Deluxe Dragster Demolition Stomper Demonic Junker Dependable Quinjet Dermotaxi Detention Chariot Dodgy Jalopy Dragonfly Suit Dreadmobile Dune Drifter Dusk Legion Dreadnought Earthrumbler Enchanted Carriage Esika's Chariot Fell Flagship Filigree Racer Fire Nation Warship Flamewar, Streetwise Operative Fleetwheel Cruiser Flywheel Racer Foreboding Steamboat Funeral Longboat Futurist Sentinel Gastal Thrillroller Getaway Car Ghost Ark Gilded Assault Cart Goldbug, Scrappy Scout Golden Argosy
I think you play two copies in the sideboard of a deck that can cast Locke
