Reign of the Pit — ruling 1

You choose which creature you are sacrificing first, then each other player in turn order does the same. The creatures are all sacrificed simultaneously.

Reign of the Pit — ruling 2

Use the powers of the creatures as they last existed on the battlefield to determine the value of X, even if they were negative. For example, if the sacrificed creatures were 3/3, 5/5, 0/4, and -2/2, the Demon will be 6/6.

Reign of the Pit : règles, fonctionnement et interactions (MTG)

Reign of the Pit 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

Each player sacrifices a creature of their choice. Create an X/X black Demon creature token with flying, where X is the total power of the creatures sacrificed this way.

How it works : Reign of the Pit

Original English text — Wizards of the Coast / Scryfall

#1May 29, 2014· Wizards of the Coast
You choose which creature you are sacrificing first, then each other player in turn order does the same. The creatures are all sacrificed simultaneously.
No other card is named in this ruling.
#2May 29, 2014· Wizards of the Coast
Use the powers of the creatures as they last existed on the battlefield to determine the value of X, even if they were negative. For example, if the sacrificed creatures were 3/3, 5/5, 0/4, and -2/2, the Demon will be 6/6.
Card named in this ruling
Demon