Nay, in fact, the spider/human beasts have always been on the mainland.
Ignored as it contradicts previous lore. If you can reconcile this with the driders driving the humans off the mainland
after they developed advanced societies and technologies, I'll add it.
Yes, Chaos Magic, and it is wielded by the Gnomes of the Northern Wastes.
The spiders don't go there as they would rather not be turned into chickens and eaten.
Why have the gnomes done nothing to strike at the spiders?
Because they don't exist. Previous lore indicated that the only races are humans, orcs, and dwarves.
Runic etching is an artform normally used for entertainment. Its origins, lost in time, come from the extinct race of elves, who could cast spells of great power with large complex patterns.
Dueling with wooden weapons is also a favored passtime.
Why did the Elves die?
They didn't. As noted, only humans, dwarves, and orcs exist.
Cities exist amongst the isles mainly for religious activities or trade, usually both.
And also factories and stuff.
Pterodactyl were made by the Elves in an attempt to colonise the mainland. It didn't end well.
If the elves somehow manage to fit in with "there are only these three races" tidbit, I'll add this.
A meritocracy, wherein the citizens who contribute the most to society (evaluated using a very complex mathematical system) have the most say. Note that most contributive does not by any means mean richest.
Ditto for gnomes.
Ascendence Of The Death God.
Originally there was no Death God, during the last days of the ElvenGnome war, an Elvish Necromancer ascended to Godhood, killing the majority of his race in the process, leaving them easy pickings for the Gnomes.
Reconcile this with the lack of elves and gnomes (and explain the absence of a death god previously), and we're good.
The elf did it because he wanted to fulfill a great prophecy of a "Dwarf Fortress". It was greed and insanity that turned him down the path. His name is Toady, the first of his clan, or to put it simply, Toady One.
What is the "Dwarf Fortress" prophecy that the elf searched for?
That GreatWyrmGold would refuse to answer this question, partly because it's silly but mostly because of continuity errors.