Quote from Scienceboy1 >>

 first i never said that he was using warlock's mystic arcanum

Yeah, it's an exploit due to bad wording in the 2024 (they removed the word 'warlock' from the ability to recover a spell slot), though I'm not sure how it was actually useful in a duel since recovering a spell slot requires the magic action and a duel probably won't last long enough for you to both regain and use a slot.

It seems odd to try to draw any conclusions about a feat being overpowered based solely on one incredibly unusual incident.

Quote from Scienceboy1 >>

Quote from 6thLyranGuard >>

Quote from Scienceboy1

 The fact that the character was broken is irrelevant, but the point I made is not. 

Warcaster is broken because pretty much any spell is cast with an action

 False.  The chararcter was broken on multiple levels (Tier IV is inherently unbalanced, the character had too many magic items, and they were using an item in a way that's against RAW- a warlock's mystic arcanum do not use spell slots).  As such, it's not a valid demonstration of the feat being OP because the overwhelming majority of players won't have any of that.

 first i never said that he was using warlock's mystic arcanum

 Then we add "a cheesed multiclass build in order to exploit a magic item in a way it wasn't intended to be used" to the pile.

You are misreading that guideline and presenting it out of context. The full text reads:

Combat Is for Enemies. Some rules apply only during combat or while a character is acting in Initiative order. Don’t let players attack each other or helpless creatures to activate those rules.

This is clearly saying that you should not let characters initiate "combat" with each other just so they can use a particular power or ability. It is NOT saying that other characters do not count as creatures and therefore don't provoke attacks of opportunity. The designers chose to change the wording in attacks of opportunity and War Caster consciously, not by accident.

And beyond the fact that nothing in the 2024 rules contradicts the use of beneficial spells on allies as part of the War Caster feat, it makes sense; a combat trained cleric would of course focus on being able to apply rapid and reactive medical care just like any combat medic.

As someone said, that is descriptive text, not rules text. The actual text of the rule, which I already posted, very clearly says creatures provoke attacks of opportunity, not just enemies. And that is a change in the wording from the 2014 rules, which means it is intentionally phrased that way. 

You are arguing that War Caster is overpowered because of something that happened to you in a specific situation. It's reasonable for other people to ask about that situation, and to point out that it's an extremely uncommon one to be in, and therefore not really a good way to judge whether War Caster is overpowered.

Quote from Scienceboy1 >>

Quote from wagnarokkr >>

You are arguing that War Caster is overpowered because of something that happened to you in a specific situation. It's reasonable for other people to ask about that situation, and to point out that it's an extremely uncommon one to be in, and therefore not really a good way to judge whether War Caster is overpowered.

 I also gave a good reason why it's overpowered in this post

 You seem to be on your own, so feel free to think it's OP.  Your arguments are not convincing.

1)  This thread is friggin hilarious.

2) I can see some powergamers somewhere collaborating to be hostile to each other out of combat so that during combat they can justify pulling off something like "I left his reach right after stabbing him with my dagger so now he should be able to use Warcaster to cast Heal on me as a reaction"  and rules lawyering it; and, hey, technically, those players are hostile to each other, so Warcaster would technically need to apply.  Bad PC behavior, but great rules lawyer.