Divergent Growth

One green mana turns every land you control into a rainbow source for a turn, and that is either trivia or a key, depending on what you are trying to cast. As honest fixing it is wasteful: it costs a card and a mana to filter color you could get more cleanly from a single dual land, and the conversion evaporates at end of turn. The reason it exists is the splash you cannot afford to build a manabase around: the off-color combo piece, the spell whose color requirements your deck flat-out ignores until the turn it matters. Unlike a ritual or a mana rock, it adds nothing to your pool; it is purely a filter, retuning the lands you already have rather than accelerating you. Its payoff grows with how many lands you have to convert: with one land it does almost nothing, but with a full board it briefly erases every color constraint in your deck at once. The instant timing is the part that earns its keep, letting you hold up one green source and divert the rest of your lands toward whatever the turn demands, firing in response to a trigger or before an opponent's combo resolves. That flexibility is also the ceiling. A card that does nothing but enable other cards has to be enabling something worth the two-for-one, and a deck precise enough to want this is usually precise enough to just run the right lands instead.