Regarding summons in games that have them:

1. Should Summoners be their own class (who typically gets nothing but summon spells), or should summons be spread out between other spellcastes (who typically do more than just summon)? Examples of Summoners being their own class include Wizardry Empire series, Wizardry Summoner, Elminage series. Examples of summons being distributed between classes include Bard's Tale 1-3, Baldur's Gate/Icewind Dale eeries, Wizardry games (5+ and others not listed here; doesn't apply to 4 because there's only one PC class available).

2. How long should summons last? Do you prefer them to be temporary spells, typically lasting for one battle (in games where many spells normally wear off at the end of battle)? Or do you prefer longer lasting summons, which typically last until killed or (in some games) you return to town? Or maybe you prefer to have Final Fantasy styles summons, in which summons are really just standard spells with fancy animations? Examples of temporary summons include Wizardry
5-8 and the Wizardry Gaiden series, Baldur's Gate and Icewind Dale series, Elder scrolls series (Battlespire/Morrowind onward). Examples of longer lasting summons include Bard's Tale 1-3, Wizardry Empire/Summoner/Elminage (same ones where Summoner is its own class), Geneforge series (shaping is basically summoning with a different name), and Wizardry 4 (summons here aren't the result of spells, but rather are done at specific locations in the dungeon).

So, what are your preferences here? I personally prefer to have summoners not be their own class, and for summons to be long lasting.

Edit: Thought of another question: Should summons be controllable by the player, or should they act according to AI? I happen to like them being AI controlled, as long as they don't have resource constraints (or you can just summon another if they run out) and the AI is simple but functional.

Best summoner I played was from Diablo 2: Median XL - Ultimative.

IWD2 pre-patch scaled summons into Festering Drowned Dead and Apocalyptic Boneguards: broken af.

Something like Diablo 2's Necromancer, or Grim Dawn's Shaman/Occultist. They are just the perfect summoners in any game ever!

I'm not familiar with that game. Could you please explain how summons work with respect to the questions in the first post?

I rarely use them. Some games you're given little or no control over them. And often they're too weak to do much but get in the way of your melee attacks.

Summoning never really caught on with me.

That reminds me that I actually wanted to replay Diablo 2 as a summoner character. My first playthrough was as a warrior or such, IIRC.

I often play games where that's not a factor, because the game does not track position.

The original Bard's Tale is an example of this; there is a party slot that is reserved for summons (so the summon doesn't take a spot a regular character could take), and any of your first three characters can melee attack, regardless of whether you have a summon. I like to summon an illusionary Red Dragon which will sometimes breath fire on the first group of enemies, frequently obliterating the entire group.

Bard's Tale 2 and 3 made the special slot a regular party slot, so using a summon does take up a spot that a regular party member could take, but summons could still be useful. In Bard's Tale 2, one of my favorite things to do is find an enemy that casts Mangar's Mallet (most powerful attack spell in the game) and cast the spell that turns an enemy into a party member.

Elminage Gothic is like Bard's Tale 1 in terms of the summon taking a special slot, but the thing I don't like here is that you basically need to devote one of your characters solely to summoning, and the chance of turning many enemies into summons is way too low.

Is this limited to combat summons?

Geneforge saga has summoning at the core of both lore and gameplay. It's about creating living beings and how they are used. You can't create them in combat (some enemies can, though), but once you do they are with you until they die or you reabsorb them. They level up and can be controlled if they have at least 2 int points.

I am mainly thinking that it applies to summons that give you a party member, even if that party member is more useful outside of combat than in.

There are a few games with other types of summons. Many of the Final Fantasy summons are really just normal spells (usually attack spells) with fancy animations. Romancing SaGa has summons that act as transformation spells, in the sense that they replace the caster (one even replaces the caster with a clone). Some games (Final Fantasy 10) have summons that replace your entire party while in effect.

I'm most interested in the questions I put in the first post, like how long summons last, and whether summons are a character's sole focus or an ability that is incidentally given to other classes.

For question 1, it partly comes down to how the game uses magic in general. If there is magic specialization or classes that can have a character focusing on, say, fire spells or nature spells, then it would make sense for a fire specialist to be able to summon salamanders and fire elementals along with the other typical fire-based spells, nature specialist could have wolves and birds of prey, etc. Throw necromancers in the mix with undead and raising regular dead.

For question 2, I think this also partly depends on how magic is used. For example, spells that are memorization-based (a la the Infinity Engine games) versus mana-based (a la Divinity 2 that I'm playing now).

And how is the book on "Lots of very weird questions about xRPGs, principally focused on jRPG's and Wizadry series as if asked by an Amazon bot" going by the way?

Summons and summoners are lame per se. I used them a few times (e.g. the final fight in Baldur's Gate...I pretty much abused wands of monsters summoning for that one...), but it always felt lame, a bit like cheating...a character that lets others do the fighting and sits back, just isn't fun for me.

In the case of Joseph from Summoner, about six feet under :p

Medium rare.

Well it really depends on the play style and how other forms of magic are handled. In a turn based it is much easier for the player to exert more control over a summon. This would not work in an action RPG.

I really like the way summons work in the Shadowrun Returns series. The character can summon an entity and control it, but if they try to make it do too much they can lose control and the summon is then free to do what it wants. I'm less impressed by the summon mechanics in The Elder Scrolls games, for example Morrowind. Any class can cast a summon spell identical to a Summoner class, with the exact same summoned entity lasting the exact same amount of time. The only hurdle is Mana cost a skill level based chance of failure.

I would rather a system that allows any character class to cast weak, temporary summons but a specialist Summoner class would be the only one who could cast permanent summons. Higher level Summoners should even have the ability to have multiple permanent summons at a time. There should be some sort of additional step involved to keep things fair. Going back to The Elder Scrolls for example, a permanent summon would require having specific items and performing a ritual. So summoning a fire based deadra would use Mana, fire salts, animal parts such as hide and a meditation period forcing you to rest for an hour. Having a permanent ally like this could be very powerful, but the player shouldn't be able to summon a dozen of them during an ambush. I'd even go a step further and apply some sort of restriction while permanent summons are active, say a -50 or -100 penalty to Max mana for each permanent summon the player has to signify the concentration required to keep them active. It might even be better, from a gameplay stand point, to apply the penalty to Health instead of Mana.