I don't think any world quest has been made in OT.
Devovorga requires SHITloads of LUA, it's unreal, you need LOT'S of shit, it'd be the heaviest LUA shit ever, okay I said SHIT enough times, but you get my point.
In short, there's so much LUA involved that you shouldn't expect to get it for free.
The easiest world event quest that is possible to make is Last Creep Standing, it's still difficult but the easiest.
@bogart, it's a world quest that CipSoft made in September
http://tibia.wikia.com/wiki/Rise_of_Devovorga/Spoiler
Steps to complete world quest Devovorga:
* Kill all bosses at the same time and leave the room, make sure nobody kills the bosses when they spawn later.
* Kill all the Bloom of Doom in Vengoth and a large spawn of Spawn of Devovorga will come out, once you've have killed all the blooms you'll get teleported to the hole, go down and kill the Spawn of Devovogra as soon as possible.
* All the bosses will spawn again. MAKE SURE YOU HAVE KILLED ALL SPAWN OF DEVOVORGA BEFORE YOU KILL ANY BOSS.
* Wait in the room because more Spawn of Devovorga will appear.
* Kill all the bosses again at the same time.
* Kill all the Bloom of Doom and the Vulnerable Cocoon again to make Devovorga finally spawn.
* Now you can kill Devovorga.