Thermo-Alchemist

• WOTC Official Reminder Textofficial rules
  Defender — This creature can't attack.

• WWizards of the Coast2025-01-24
  Official Ruling
  Thermo-Alchemist’s triggered ability resolves before the spell that caused it to trigger. It resolves even if that spell is countered. Players can cast spells and activate abilities (such as Thermo-Alchemist’s own activated ability) after the triggered ability resolves but before the spell that caused it to trigger does.
• WWizards of the Coast2025-01-24
  Official Ruling
  In a Two-Headed Giant game, Thermo-Alchemist’s activated ability deals 1 damage to each of your opponents, resulting in the opposing team losing 2 life.

Rulings via Scryfall