The Zombie Berserker creature token enters the battlefield as a 2/2 creature. Any abilities that trigger when a creature with a certain power or toughness enters the battlefield will see the token enter as a 2/2 creature.

You decide whether to pay as the enters-the-battlefield ability resolves. If you do, you immediately create the Zombie Berserker creature token and attach Draugr's Helm to it. No players may respond to your decision to pay or not, and no player may take actions during this process.