The PortalSpawn Event is fired when an attempt is made to spawn a nether portal. If cancelled, the portal will not be spawned.

You will need to cast the event in the function header as this class:
crafttweaker.event.PortalSpawnEvent
You can, of course, also import the class before and use that name then.

BlockNeighborNotify Events implement the following interfaces and are able to call all of their methods/getters/setters as well:

• IEventCancelable
• IBlockEvent

The following information can be retrieved from the event:

ZenGetter	ZenSetter	Type
ZenGetter valid	ZenSetter ​	Type bool
ZenGetter height	ZenSetter ​	Type int
ZenGetter width	ZenSetter ​	Type int

The following information can be retrieved from the event:

ZenGetter	ZenSetter	Type
ZenGetter world	ZenSetter ​	Type IWorld
ZenGetter blockState	ZenSetter ​	Type IBlockState
ZenGetter block	ZenSetter ​	Type IBlock
ZenGetter canceled	ZenSetter canceled	Type bool

ZenMethods

• event.cancel(); Method, returns void (nothing). Can cancel the event and stop something from happening

ZenGetter	ZenSetter	Type
ZenGetter position	ZenSetter ​	Type IBlockPos
ZenGetter x	ZenSetter ​	Type int
ZenGetter y	ZenSetter ​	Type int
ZenGetter z	ZenSetter ​	Type int

valid will return true if the portal is valid to be spawned, false if it cant spawn the portal like this.