The Inner Light 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

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.) I — Return target green or white creature card from your graveyard to the battlefield. II — Choose target creature. Whenever it deals combat damage to a player this turn, you draw that many cards. III — You gain life equal to the greatest power among creatures you control. Create a Treasure token.