Chroma abilities check only mana costs, which are found in a card’s upper right corner. They don’t count mana symbols that appear in a card’s text box.

Chroma abilities count hybrid mana symbols of the appropriate color. For example, a card with mana cost {3}{U/R}{U/R} has two red mana symbols in its mana cost.

Light from Within affects each creature individually. For example, if you control a creature with mana cost {1}{W}{W} and a creature with mana cost {W/B}{W/B}{W/B}{W/B}{W/B}, the first creature gets +2/+2 and the second creature gets +5/+5.