Does the extra damage from Great Weapon Master to Bonus Action attacks and attacks using Sentinel?
Someone told me that the extra damage from it doesn't apply since it's either a Bonus Action or a Reaction. I figured I would seek additional input and feedback.
It only applies to attacks made during as part of the Attack action, so no opportunity attacks or even bonus action attacks. In fact, a character using True Strike as a Magic action would not get to apply the bonus damage even though they are making an attack with their action.
The second benefit of Great Weapon Master (Heavy Weapon Mastery) could interact with a weapon-based cantrip (e.g. Booming Blade, Green-Flame Blade, or True Strike) if the cantrip is cast as part of the Attack action (for example, thanks to Eldritch Knight's War Magic, College of Valor Bard's Extra Attack, or Bladesinging's Extra Attack)
The third benefit (Hew) can interact regardless of whether you make the attack from those cantrips using your Magic action or your Attack action.
Does the extra damage from Great Weapon Master to Bonus Action attacks and attacks using Sentinel?
Someone told me that the extra damage from it doesn't apply since it's either a Bonus Action or a Reaction. I figured I would seek additional input and feedback.
TIA
It only applies to attacks made during as part of the Attack action, so no opportunity attacks or even bonus action attacks. In fact, a character using True Strike as a Magic action would not get to apply the bonus damage even though they are making an attack with their action.
The second benefit of Great Weapon Master (Heavy Weapon Mastery) could interact with a weapon-based cantrip (e.g. Booming Blade, Green-Flame Blade, or True Strike) if the cantrip is cast as part of the Attack action (for example, thanks to Eldritch Knight's War Magic, College of Valor Bard's Extra Attack, or Bladesinging's Extra Attack)
The third benefit (Hew) can interact regardless of whether you make the attack from those cantrips using your Magic action or your Attack action.