they took it out as it was overpowered. you can only get it through researching magic now.

It doesn't make much sense to me that they left in the rest of the summoning spells which you can still get really quickly, and are just as overpowered.

Permanent, unlimited, nigh- unhittable rock giants at spell level 4 with no resource costs, are just as overpowered.  Even cheap summon familiar at level 2 or whatever is powerful enough to make it to mid-game without having to field troops.

I disagree with the degree of your statement.  You can get "decent" summons at level 2 or 3. Summon familiar isn't an overpowerful unit, but it will let you deal with most creatures on the map, and take over early cities, until you get a better one. Not as good as the uber bear you could get within ten turns before, but good enough.  Even if it only lasts a couple battles, it is cheap to re-summon (cheaper than using offensive magic), and frees you from the cost of fielding troops, or having to worry about their health.  Who cares if a summons dies? You just make another one effortlessly.

The summons you get at level 4 about a third of the way through the game like the rock giant, are *game winning*, allowing you to conquer half the map while teching up your conventional troops to deal with end game.

Summoning, like most of the magic system needs completely overhauled.  Being able to summon *permanent* units with minimal research, without associated resource costs, is overpowered and takes the place of conventional troops for much of the game.

Summoned units should only last for one turn, or one battle like in most games, and have their cost adjusted accordingly.  Even at twice the price of a basic attack spell, they would still be a bargain, as a spell that does persistent damage over time to multiple troops, while simultaneously protecting you from damage. Permanent units should have to be researched and paid for with limited resources (for instance with Shards that we have little use for now), or recruited, like any other permanent unit.

I think there would be far more satisfaction from running across a rock giant you're able to "recruit" on the map with the proper research, or getting control of a resource that allows you to *build* them, rather than being able to effortlessly summon an unlimited supply of permanent godlike creatures who get a free area attack every turn.

This has not been my experience. But I have thus far played only on "normal" difficulty  while I figure it out, and I aggressively pursue summoning spells after I get a basic attack spell, as they are the best, most cost efficient use of magic in the game, and the other spells aren't very crucial.  Obviously harder difficulties and larger and larger maps will skew this, but I want to experience the baseline game while I learn the ins and outs of tech trees and rules.

I have yet to play a game doing this where I couldn't roll the majority of the map with a simple, cost effective 8 point rock giant.  The familiar is plenty good enough to handle spider swarms and bandits in the first third of the game to level up your Sov and take out a few early cities with. 

Sure, eventually you'll start running into some squads, and Sovs with similar summoning ability.  But by that time, you will have conquered so many cities with access to so many resources, and been able to build up your infrastructure to such a degree by not having to build any real armies, there's no way they can stop you. And by that time your own killer companies are rolling off the assembly line. I've yet to play a game where using free summoned units didn't feel like cheating.

I think summons should *supplement* the traditional army units that the game, resource system, economy, and research trees are built around, not *replace* them for half the game.  At the very least, the summoned units should be either nerfed a bit, or moved to a higher level, and they should have a material component cost, as well, like shards.  It makes perfect sense to need earth crystals to summon an earth creature into permanent form. 

I'd much rather have to recruit, research, or build any permanent units. Using exploration to recruit new units you couldn't really plan for, and capturing a resource that lets you build that monster, seems what the game is built around.  Summoning should work fundamentally differently.