HTTT has some frustrating diplomatic issues...

[Darkrenown]

Secundo, theres the issue of alliances. The Ai regularly Dows people without CBs now, and this inflicts large stab hits on the player if he allies AI nations. This is, IMO, unacceptable as a game mechanic. The AI ought to either not DoW without a CB, or the player ought to either not receive a call to arms when such a thing happens, or to benefit nontheless from an "Aid an Ally!" CB and get no stab hit. A third option would be to ensure that calls to arms without a CB can be declined without damaging either Relations, Trust, Prestige, nor Breaking the Alliance.

Sometimes you just don't have a handy CB but you want to DoW anyway, so I wouldn't forbid the AI from DoWing without one.

Not getting a penalty, or getting a reduced one for declining a call without a valid CB was something I thought about too during the beta. However I concluded that it didn't really fit with the alliance system. When you sign an alliance in EU it's a FULL alliance, you're agreeing to support your ally no matter what, and if you don't live up to this you suffer for it by losing prestige. If you're not willing to support a nation fully, including if they dow without a CB, you shouldn't be allying with them.

 

[Darkrenown]

You're still supporting someone being naughty though. Sometimes you're damned if you do, damned if you don't.

 

[Trin Tragula]

The problem to me seems to be that the AI is actually a bit too opportunistic), it will expand when the possibility is given and does so well. However it won't take into much consideration what to do with the things it has conquered afterwards. It also seems to not consider how to defend it's gains and therefore it will often overstretch and then implode.
The above behaviour is also why it's supposedly become harder to play nice with it.
This is just from what people have been reporting on the forum and from my own one game so far though.

 

[Darkrenown]

In my short game last night, I got a CB (aid-an-ally) after I refused the call to aid him. It appears there is a lag between getting CB and being asked to join a war. This leads to expensive stab cost for honoring them, and the cheap exploit of joining the effort as a leader of your own war, afterward when you no longer have an ally in the war.

No, that's not true. You get the Ally CB when your ally is at war with someone and you are not, you got it briefly as your alliance status and CBs are only checked at the end of the month. I suppose you could "exploit" this and DoW with the ally CB, but it doesn't allow taking provinces etc.
If your ally has a valid CB you don't get a stab hit for joining.

 

[GAGA Extrem]

I think this CB has been added to prevent DOW exploits.

Before HTTT, you could always DOW alliance minors to prevent strong allies from going to war as they should.

Example:
FRA is allied with RUS and BAV, but RUS is not allied with BAV. If ENG sends a DOW to BAV, FRA will get a call to arms, but RUS will not. With HTTT, RUS now gets an "Alliance CB" against ENG and can join the war.

This exploit was esp. awful for MP games - and now it is fixed!