Phosphorescent Feast — ruling 1

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.

Phosphorescent Feast — ruling 2

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.

Phosphorescent Feast : règles, fonctionnement et interactions (MTG)

Phosphorescent Feast is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

Chroma — Reveal any number of cards in your hand. You gain 2 life for each green mana symbol in those cards' mana costs.

How it works : Phosphorescent Feast

Original English text — Wizards of the Coast / Scryfall

#1August 1, 2008· Wizards of the Coast
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.
No other card is named in this ruling.
#2August 1, 2008· Wizards of the Coast
Chroma abilities count hybrid mana symbols of the appropriate color. For example, a card with mana cost has two red mana symbols in its mana cost.
No other card is named in this ruling.