Double Green costs twice as much as a Green Bloon or a Swarm Green Bloon, but still has 2 charges and pairs well with health boosts such as Fortify. However, the Double Yellow Bloon usually overshadows it due to virtue of highest HP 1-delay Double Bloon.
Similarly to playing two Greens, playing one Double Green is enough Bloontonium for unlocking Amelia's Bloon Shield.
Although Double Yellow Bloon is generally better for OTK decks, Double Green with Eerie Lifeforce and two Quick Ready costs exactly 20 Gold, requiring no extra Gold or discounts to make this combo affordable.
If paired with Zee Jay's Passive Enhancements, a Double Green combined with three Fortify and Quick Ready does exactly enough damage to OTK an opponent without shields, Defenders, the passives of Quincy or Adora, or 0-delay stoppers.