Demon Berserker 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

Menace (This creature can't be blocked except by two or more creatures.)

How it works : Demon Berserker

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 Demon Berserker.

The Bloodsky Massacre

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.) I — Create a 2/3 red Demon Berserker creature token with menace. II — Whenever a Berserker attacks this turn, you draw a card and you lose 1 life. III — Add {R} for each Berserker you control. Until end of turn, you don't lose this mana as steps and phases end.