The kicker is that when one of your creatures dies, opponents lose one life, and when an opponent's creature dies, you gain 1 life
Colossus matches up very poorly into the ever present Impermanences in the format, and decks are already prepared to play around Droll & Lock Bird, which practically any Fiendsmith line outing the Fusion before it truly stops them
This card gains 500ATK for each dragon monster your opponent controls, or is in their graveyard
3 Eustass "Captain" Kid Stay Guarded, Stay Deadly Eustass Kids effect is not only powerful but also rewards you for stacking your deck with Supernovas
Some non-activated effects apply while on the field (like Continuous Effects), but also apply in some other location(s), apply while face-down, or apply when the card leaves the field, hence are unclassified