Stampede Surfer

Haste
Whenever this creature attacks, for each opponent, you create a 2/2 green Boar creature token that's tapped and attacking that opponent.

Ravnica: Clue Edition

Haste
Whenever Stampede Surfer attacks, for each opponent, you create a 2/2 green Boar creature token that‘s tapped and attacking that opponent.

Although the tokens enter the battlefield attacking, they were never declared as attackers. Abilities that trigger whenever a creature attacks won't trigger. If there are any costs to have a creature attack, those costs won't apply to the tokens.

The token creatures all enter the battlefield at the same time.