Warlock spell+invocation interaction

[Wilb]

Just to be clear, I've scoured forums and the sage advice website and found no info on this.

Considering the way Thirsting blade is written, would it trigger on the Attack action granted by the Haste spell? Considering that Haste says "Attack (one weapon attack only)... action" and the invocation says "you can attack with your pact weapon twice, instead of once, whenever you take the attack action", would the specificity of requiring a pact weapon trump the general effect of the Haste spell?

My brain is giving up on me and I can't seem to find a reason for this combination not to work, please guys, point me to where I've made a mistake.

EDIT: I know Haste is not a Warlock spell, but they can get it without much fuss by going sorlock or a similar multiclass.

[SorO_Lost]

Just to be clear, I've scoured forums and the sage advice website and found no info on this.

That's because it's fairly obvious. Haste calls out a specfic limitation of what you can do with what it gives. In the rule stack, everyone can only make one attack anyway so the fact that is calls out such means it already acknowledged things too.

Just expand your search out.

Jeremy Crawford: The haste spell states that you can make only one weapon attack with the action it provides.

[Wilb]

Thanks for assisting me with my brainfart!

I thought that due to the extra attack happening only if done with the pact weapon, the invocation would act "after" the spell effect, as in:

• Haste allows you to take an extra action, if you take the attack action with it you can only attack once.

• Thirsting blade makes it that when you take an attack action, you attack twice instead of once if you do so with the pact weapon.

• You could attack twice with the Haste extra action, as long as its done with your pact weapon.

Turns out I reversed the priority of the rules, it seems. 1 less broken rule to think about.

[bruceleeroy]

You've arrived at the right conclusion for the wrong reason. Haste doesn't let you take the "Attack Action", it lets you make one attack. The attack action is it's own category of Action and it may let you make one or more attacks and/or trigger other effects.

I wish they had used a different name for it.