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.
Similarly to playing two Greens, playing one Double Green is enough Bloontonium for unlocking Amelia's Bloon Shield.
Double Green is the only 1-delay 4 cost bloon, mostly notable if 4 Bloontonium is an important breakpoint alongside putting down fast pressure on the opponent. It is also one of two 4-cost bloons with 2 charges, the other bloon being the Shield Gas Bloon. This can be useful for precisely filling out enough Bloontonium for Amelia's Grand Disappearance after playing two BFBs.
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, or the passives of Quincy or Adora.