I would wait for an official errata change, versus what anyone states as an opinion.
No opinion required, just read the rules carefully, then DM decides for their own game.
I would wait for an official errata change, versus what anyone states as an opinion.
So our valued player responds, along the lines of paraphrasing the text of the two feats, reminding me that he spent two feats to get that combination, making a minimal narrative justification for the ability, and then finally, saying, "I built my character around this concept." That last line really put my hackles up.
Permissions for multi-classing or feats aren't really an idea in DnD. A permission is an idea from the Fate system which is a logical narrative justification beyond just having mechanical access to the ability, e.g. "must belong to an appropriate airforce organisation" for the "Top Gun Pilot" stunt.
It's my understanding that it's not really a matter of permissions. Nothing stops a player from taking any particular feat or two. The question is whether the feats work in concert, and considering that the RAW of the rules leaves some grey areas, it then falls on the player to beseech the DM for game-specific clarification, and of course in this case the player is trying to get the more favorable interpretation/ruling.
Well feats and MC are optional in this edition so technically yes, you do require permission.
But in this case, there is no grey area between warcaster and polearm master. Warcaster doesn't say "you can take an AoO with a spell, except with a reach weapon". In fact, it seems to specifically designed to work with a staff which is pretty much THE spellcaster weapon.
Apparently not because Mearls waded in with the nerfbat for no reason at all.
War Caster specifically states your are NOT taking an AoO with a spell. What War Caster does is it takes the AoO you would have gotten (no matter if it's granted by Polearm Master, or whether it's triggered by a opponent moving away) and tosses that it out the window, and replaces it with a reaction spell. So the trigger happens, then a second trigger happens, then spell happens.
Edit: The grey area I was speaking of was whether or not the AoO granted by Polearm Master has reach or not. The entry on Reach has wording that COULD be interpreted in two ways. The conservative reading means it's not at 10', and the liberal reading says it's at 10'.
Shiver me timbers, you're right! That's pretty straight forward then. Polearm Master doesn't work with Warcaster because Warcaster replaces the AoO and Polearm Master works on an AoO.
I'm not sure why the area you've pointed out is a grey area though, 3 of the 4 weapons mentioned in the feat have Reach but it doesn't say it grants Reach at all.