PvK
You give me more experience/ideas than I actually have
!
I was rather explaining than IMHO it's quite pointless to put 25+ gp in a quite subpar unit with many nations, even if upkeep free ... because it's also immobile and impossible to command.
It may have some use in SP games to strengthen some defense, but in MP it looks stupid.
So I've no experience with trying 30+ defense... and my fellow and more experienced gamers (such as Pocus) think the same way. I prefer to use the 500 gold it take from def 20 to 30 to buy real units !
In the same spirit I think that the basic defense unit should be at least good enough to warrant its cost, even if low. Cardaces and Velites don't (Velites having at least javelins...). Arco is additionally plagued by having Lt Cav as 2nd type of defense troops, bwaaaaa
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