What’s the best way to spend a Sunday morning? Annoying the designers of D&D. But I have an excuse: I reealllyy needed an answer to this one. I give you: The Official-ish answer to the Sentinel Problem.
The short version: Sentinel triggers after the triggering attack resolves. Which makes a lot of sense. I mean, if not, what is the Sentinel reacting to? He’s reacting to the swing of the weapon. Unless he’s faster than the attacker, how would his attack resolve first? So for my tables, it will be RAW from now on.