Melira, Sylvok Outcast and Puppeteer Clique would both be good cards in the deck, and together with a sac outlet like Ashnod's Altar allow control of every creature in every opponents graveyard
I believe that we're getting pretty close to making a generic deciduous version of this mechanic
Stay safe, stay healthy, and stay out of the sun
Count nonland mana sources (like Birds of Paradise and Mind Stone, et al.) as half of a land
What keeps it back here at #3
Getting benefits for opponents doing things is usually whites thing (Monologue TaxMonologue Tax, Charismatic ConquerorCharismatic Conqueror, Smothering TitheSmothering Tithe, etc.), but this is actually a callback to the red card Harsh MentorHarsh Mentor, which deals two damage to opponents for using activated abilities