There's been much discussion of the zmey but I wanted to add my thoughts since I've been thinking about them recently. They can be quite a pain to deal with but the particularly thing that prompts me is I'm tired of seeing wars begin with each side launching their squadrons of zmey at each other. I want more variety!
I think there's a few things that contribute to their frequency. First, they are close to an optimal use of F gems. Aside from their fellow EDM summons, the Ember Lord and the (unique) firebird, I believe the entire list of F summons is fire drakes, scorpion beasts, summer lions and fire snakes. These aren't horrible summons and in fact the fire snake used to be quite a popular summon and was the big loser in the zmey's rise to prominence. But something that's notable about the list is the lack of any commander, let alone mage, summons. Compare that to its opposite element of water (a path that I think has a fairly comparable usage patter in terms of forging and spellcasting) where you have several mage commanders as well as troops that have a variety of situationally useful abilities such as amphibious, cold aura, recuperation, awe, regeneration, high HP, magic weapons.
Later on, you'll presumably be able to summon ember lords and you might think at that point you'll start seeing fewer zmey but I'm not sure if that's the case because of the second, and more important, point: namely that zmey are best in class in their raiding category. Because of that there's a strong case to keep using your F gems to summon zmey and use other paths to summon SCs, despite the fact that Ember Lords are excellent units.
There are some nations (glamour nations come to mind) that will still find it cheaper to use other units for raiding but for many nations you won't be able to beat the cost/utility of zmey (and even raiding capable nations may find zmey a useful supplement to their own units). Compare the cost of a zmey with a minimally equipped bane lord with flying boots and a frost brand. The bane lord is far more vulnerable for almost the same cost as the zmey. And of course if he's killed, your opponent may well recover some of his equipment. Don't like the bane lord example? Feel free to substitute another unit but I think you'll be hard pressed to come up with something that has the toughness and crowd clearing capability of the zmey for the same price point. Your best bet may well be the zmey's fellow EDM summon, shishis. Unlike the zmey they can cloud trapeze into enemy territory but they lack flight so once there they can't jump around like zmey. But I think even in this comparison the zmey comes out ahead because of their toughness (including multiple lives) and large AOE attack. It's also worth noting that A gems have a different usage pattern. I frequently play A nations and the last thing I want to do is spend A gems on summons given their value for fueling cloud trapeze and battefield magic. I think F nations wouldn't have the same hesitation using F gems for zmey.
Another advantage of zmey over shishis is their synergy with lychantropos' amulet (disclaimer: I despise this item
). You will likely want your shishi's to cast some buffs, particularly mistform. The zmey has no such need, making it a perfect candidate for the lych. amulet. Not only do you get regen at half the normal price but being berserk removes an angle of attack that could otherwise be used against you. Sure, there might be times when you'd prefer to hold back before attacking but overall this item is a perfect fit for zmey. If no other changes were made to zmey I'd advocate making lych. am 10 gems just because I've come to identify them so much with zmey.
I gather zmey will likely receive a price increase and be harder to summon and this can definitely help but I think it's also worth keeping in mind ways to promote other units as situationally useful raiders.
Calahan suggested removing their misc slots and I think that would neatly solve the problem. If that's too drastic you could reduce them to 1 misc slot. So they could still choose to equip a lych. amulet but since it would be an irrevocable decision there might be more hesitation to do so. In any case, with 0/1 misc slots it would no longer be possible to make them immune to all elements.
Another possibility is making them slow flyers that only have map move 2. This would encourage using other units to penetrate deeper into enemy territory.
Basically I think there's a value in keeping them as first class raiders - but not necessarily in most situations, as they are now.