Shadow Isles VS The Void
 

Who would win in an epic fate-of-the-world war between both sides? Why?

The Shadow Isles are a bunch of isles where undead live.

The Void is an extradimensional multi-realm evolving entity that feasts on magic.

/thread

I can do that too!

The Void is space with giant bugs.

The Shadow Isles are home to eldritch undead that bend spirits to their will, that grow stronger with each corpse.

/thread

Well, it doesn't help that some of those space bugs can accidentally step on those isles and squish them without noticing. Literally.

Though, if one of those attempts to manifest, Runeterra would be demolished anyway.

While I understand, and appreciate, what you're saying, you seem to be forgetting a few things. They have a large, and powerful, Spider beast, a Leader that is similar to Koggy's Daddy, the "Lich King" if you will, and the advantage of being undead.

Idk who would win but I would love to see a Void creature die in the shadow isle and rise as an Undead Voidling.

That would be a badass champion

Karthus ****s on all of them, end of story

Depends
If karthus had acess to the full Requeim,then GG
Also,would be possible to make undead soldeirs out of the void creatures?

Alright, this is my final serious post in this thread, attempting to legitimately answer a serious question. If you lot intend to troll each other, so be it.

The Void is, essentially, 'corruption' - its point of origin is unknown, but over the millenia of its existence, it consumed and corrupted numerous planets, changing their inhabitants and absorbing said planet's energy to continue its onslaught. The creatures it corrupted have evolved, and now make the main 'assault force'. Despite the way it seems, Void is an organized entity, and has centralized control - the primary goal being 'consumption', as in, absorbing the planets' energy resources, not simply destruction. The Voidspawn that we have seen on Runeterra are the smallest species - consumption of a world is a tedious process, and the first ones arriving have to guarantee that there will be no interference.

However, Runeterra is a special case - ever since the first Void appearances in times of distant past, their assaults have been defended, and their dilemma is that they cannot increase the intensity. Runeterra is in an unstable state, that has to be maintained - of course, they can dispatch one of the gargantuan monstrosities that have their little toe the size of Summoner's Rift, but that will simply destroy the planet. If you are hunting for food, you don't shoot the boar with a rocket launcher - and that's why we haven't seen anything larger than Cho'Gath and some Void carriers so far.

The Shadow Isles are a dark and mysterious place, that is true - sure, they are undead, they have a huge ass spider, and that 'King' figure of theirs; but are they really more powerful than the Void? Can this spider thing defeat Cho'Gath, if he was not restricted by the League, and allowed to grow to his full size? Being undead means that your soul is being held in place and bound to an already decayed body (or even without the body), through some magic means; but since the Void eats magic for breakfast, how many chances do inherently magical creatures have against anti-magic assailants?

And that, mind you, is in a scenario where the Void will still aim to conserve Runeterra. If it's, as OP said, a fate-of-the-world war, the Void will absolutely devastate both the Isles and the entire planet. It's still alive just because the Void decides it should be.

"In the Shadow Isles, Death is only a promotion"

'Nuff said.