I would say Synergy chests are more common than black chests. Rarest chests are rainbow and glitched, and I believe there's a variant of rainbow that's synergy based. I've seen no rainbow and a couple glitched chests in 200-ish hours of play.
Tfw bullet bore IS a good gun, it stuns enemies. And it homes in + explodes so that it does destroy bullets. Also it kills me whenever chat tells him to immediatly use d-pad up instead of teaching him to hookshot to steal items
How is this dude calling the Synergy Chest the rarest lol. It's not even as rare as the red chest, let alone the black chest and don't even get me started on the rainbow and glitched chests.