Originally Posted by
jfg1984
In my testing, I just applied a -20 modifier to the damage roll to ensure that the end result of the roll was 0, and in that instance, the effect also failed to activate.
So my current understanding of what you're saying is that the DMGAT effect will only activate if the target:
1. Takes an amount of HP damage equal to 1 or more.
2. Takes an amount of temp HP damage equal to 1 or more. (assuming your settings are set to treat temp HP damage as damage)
3. Takes no damage due to having a damage threshold which the damage taken value did not exceed.
The reason the effect doesn't fit for the Motivational Speech spell is that the language of the spell stipulates you will get advantage on your next attack after you've been hit with an attack. How much damage you have to take from that hit appears to be immaterial.
You could be immune to the damage type and thus take no damage, but you should still proc the effect.
At present I don't see a way to code it to automate that. To me it seems like my best bet if I want the automation is to make a small house rule change to the language of the spell to specify that you have to take at least 1 point of damage (temp or otherwise) in order to gain the benefit.