regarding 3 (Yithril): i think that's just coincidence. sometimes they will be strong, but in my games they are often really weak. guess Verga had just a streak of luck in your last 3 games

regarding 5 (Ophidians): are they considered medium? i'm almost sure they are classified as "strong" (at least their lairs with 3 of the beasts). strength ratings aren't all that reliable, though. better to learn which creatures are actually hard instead of following the rating. Air shrills for example are considered "strong", though they are usually easier to defeat than for example wolf lairs (which are classified as "medium" i think)

regarding 6. (Forest): if the town center (hub) is adjacent to the forest, you can build a lumberyard (and follow up buildings). if it expands near/into a forest, you can't (there's a fairly popular  mod that changes that rule i think - haven't played it, though [snaking mod?])

can't comment on the other points. don't know if they are bugs

i think)

In FE, you could only expand into a forest and be able to build a lumber camp IF your city started directly diagonal from a forest. So if you started right next to one, you could build right away, if diagonal, you had to expand a bit, and any further than that, you couldn't build one ever.

It's same for piers if am not mistaken.

Regarding Ophidians as being weak. Not enough info. What did you fight them with? On what world difficulty setting? They are magic immune and have nasty bites (and great initiative) so I wouldn't really see anyone tackling them until mid game (not in groups of 3 or larger). They can and will 1 shot any leather wearing units, and you can't debuff / damage them with spells, summons will die very fast that early in the game as well.

Ice elemental is not weaker than lightbringer. He's very good for it's purpose: to snare and take hits. The fact that summons are on different tiers is not related to their power directly, they are just varied types with different utilities. For example ice elemental WILL ALWAYS apply slow when hitting a target, EVEN IF the target is immune to magic, which is a HUGE bonus vs specific enemies. -25% penalty to accuracy, while good, is nothing to write home about. Especially if the targets are getting swarm bonuses.

Yes piers and logging camps can be built if your city is "next" to the appropriate resource. Makes choosing a city location a little more interesting. The mod in question is my snaking mod and it brought back the mechanic that was removed during the beta of FE.

and Tremor does work as described at least for me, it just counts the 3 turns with your current turn. Thus, it seems effectively 2 turns of immobilization instead of the 3 advertised. In fact, all turn based effects count the turn you cast it on as one of the turns... one of those quirks.

The other quirk about logging camps is that if your city is next to a forest and you build into the forest and destroy the forest to which the city is adjacent, leads to the problem of never being able to build a logging camp. So, really when ever I can build a logging camp, I build it first and immediately, otherwise I tend to forget and lose the resource forever.

About Ophidians, I just send my boar spear armed leather armored spearmen to take them down, usually takes no more than groups of 2.

For me, an Ogre/troll is more fitting to be Medium.

as for ice elemental vs lightbringer:

Ice elemental's slow effect is melee, and thus needs to be up close, however he has almost no defenses, and a moderate health pool. I find him faaaar less tanky than the lightbringer, who has both armor and health, and can freely blind surrounding enemies.

I've had a lightbringer tank a dragon (not drake), and it can tank it better than most of my metal clad swordsmen so long as it doesn't breath fire on it.

If perhaps the ice elemental could have some ranged abilities, or some decent armor stats, it would be balanced.

Are you saying you're not tackling Ophidians before you have boar spears?

There are several combinations for taking down dragons of all types (or any dangerous non-magic immune monster) without having top tier gear or high levels of troops. Most notable being Shrink spell from life school which literally halves their attack power. You might want to gain access to resist fire gear or spells before tackling them tho (especially on higher difficulty levels when a fire breath can crit over 400+ dmg) or you will lose some troops. If you don't have armor ignoring or debuffing spells for the said lizard, don't use more than 1 melee (or summons) because his swipe will hit everyone around him (and it can crit as well for silly numbers), use a high dodge or good defense unit (if using defense one don't attack with it, just keep it defending to get the bonus armor).

it's not a big surprise that the lightbringer is tanky. it's designed as a tank after all the thing with summons is, the first side branch (wisp & lightbringer for kingdom, free skeleton and the skeleton horde + horrific wail for empires) is really powerful. those spells are extremely useful in the early game. the main summoning line (ice/air etc...) is a bit weaker initially, but it also contains an extra level offthe summoner trait that will improve all summons significantly. so the choice is to pick up the side branch with great early game spells and delay the main line with the higher levels, or skip the side branch and go straight for higher levels and more powerful creatures in the main line. i think it's a meaningful choice and thus, well designed.

well some of the later summons seem to be pretty impressive, so it will balance out in the end, i guess. 

lightbringer is good, but a defender champ is better, so again, it depends on the circumstances if it's worth picking him up. also, a trained tank unit doesn't require that much to be reasonably tough. with some leather armor and tank traits, they get to about 30 defense and 30ish base HP (+2 * number of figures for each level up), so they can survive a few punches (especially if your champ has healing magic)

Ok let me clear this up a bit, shall I?

Air elemental + Haste = ultimate death machine. If you have several air shrines (upgraded), he will kill an entire army by himself on first turn as soon as you haste him.

I'll try to find the save with mine when I played Procipinee, he was 180hp 100 atk or something, 60 initiative with haste buff. Had no problem killing on his own an entire army of guardian statues in scrapyard.

The elementals scale with the amount of level of summons traits, summoner, and number of shards corresponding to their type. Of course if you play Ceresa and get trigger happy with converting all shards into death ones, your other summons apart from skelies and shadow warg will be weak.

Lightbringer is good vs melee (non spear, non upgraded bows) enemies. As soon as mages and spells come into play he's obsolete.

Go get those air shards You will be amazed.