[Twan]

For me it's pointless to make the most powerful SC unavailable via wish (after seraphs, another chassis will be the most popular, then another... it's endless). And it's a very bad idea to give to any nation an endgame summon others can never have. Balance between nations may be rock-paper-scissor in early game, but in endgame people should realise balance is only realised via the possibility for all nations to use tartarians, and about anything via wishes. Yes all nations tend to use the same things in endgame, but it's a good thing for balance as long all nations don't have a national powerful endgame SC summon.

Trying to reduce the number/availability of SCs in general is IMO a bad idea, as long the magic/initiative system stay the same. SCs (or any particular SC chassis) aren't actually overpowered compared to some endgame spells which *force* to use SCs to succeed to take provinces in endgame. Dominions without SCs would just end in big stalemates, with all battles won by defenders with mages.

For more diversity I'm rather for the addition of more non national non unique SC chassis in all paths (but uniques should also be made more powerful, or nobody will risk gems on them). Because it looks more doable than adding an endgame summon of the power of the seraph for each nation.