Flameborn Hellion — ruling 1

If, during your declare attackers step, Flameborn Hellion is tapped, is affected by a spell or ability that says it can't attack, or is affected by "summoning sickness," then it doesn't attack. If there's a cost associated with having Flameborn Hellion attack, you aren't forced to pay that cost, so it doesn't have to attack in that case either.

Flameborn Hellion : règles, fonctionnement et interactions (MTG)

Flameborn Hellion 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

Haste This creature attacks each combat if able.

How it works : Flameborn Hellion

Original English text — Wizards of the Coast / Scryfall

#1January 1, 2011· Wizards of the Coast
If, during your declare attackers step, Flameborn Hellion is tapped, is affected by a spell or ability that says it can't attack, or is affected by "summoning sickness," then it doesn't attack. If there's a cost associated with having Flameborn Hellion attack, you aren't forced to pay that cost, so it doesn't have to attack in that case either.
No other card is named in this ruling.