You can already make these effects. To make a portal set things on fire, put lava near it. Nether mobs can already come out of portals. Replace random blocks around the portal with netherrack for a corruption effect.
Rollback Post to RevisionRollBack
If anyone wants to port/remake this, feel free to do that! Or don't. It's up to you, really.
Make it, perhaps:
-Set nearby blocks on fire
-Spawn random nether mobs
The last part is kinda iffy, but:
-Make the nether portal replace nearby blocks with netherrack
Whatcha think?
If anyone wants to port/remake this, feel free to do that! Or don't. It's up to you, really.
Also, here is an awesome suggestion I had: http://www.minecraftforum.net/topic/1745550-biome-effects/
http://www.minecraft...orld-version-3/