Reverberating Summons 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

At the beginning of each combat, if you've cast two or more spells this turn, this enchantment becomes a 3/3 Monk creature with haste in addition to its other types until end of turn. , Discard your hand, Sacrifice this enchantment: Draw two cards.

How it works : Reverberating Summons

Original English text — Wizards of the Coast / Scryfall

No additional ruling has been published for this card.

Interactions with other cards

These cards' text mentions Reverberating Summons.

Great Unclean One

Reverberating Summons — At the beginning of your end step, each opponent loses 2 life. Then for each opponent who has less life than you, create a 1/3 black Demon creature token named Plaguebearer of Nurgle.