Essentially, he lets you bypass the negative effects and only reap the rewards
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

Ancient Greenwarden Atmospheric Greenhouse Bringer of the Green Dawn Circle of Protection: Green Dryad Greenseeker Emissary Green Fecund Greenshell Green Dragon Green Goblin Green Goblin, Back for More Green Goblin, Nemesis Green Goblin, Revenant Green Mana Battery Green Scarab Green Slime Green Sun's Twilight Green Sun's Zenith Green Ward Greenbelt Guardian Greenbelt Radical Greenbelt Rampager Greener Pastures Greenhilt Trainee Greenhouse // Rickety Gazebo Greenhouse // Rickety Gazebo Greenseeker Greenside Watcher Greensleeves, Maro-Sorcerer Greenwarden of Murasa Greenweaver Druid Greenwheel Liberator Greenwood Sentinel Gysahl Greens Legolas Greenleaf Llanowar Greenwidow Lurking Green Dragon Outcaster Greenblade Rune of Protection: Green Ultimate Green Goblin Wielding the Green Dragon
It has immediate heat that does not subside
He came in on his ONE DAY OFF to appraise my collection after he heard I drove two hours to meet with him