The PlayerLeftClickBlock Event is fired whenever a player left clicks a block.
It can be canceled to prevent any other events from taking place. If the player holds down the left click, the event will fire again even if it has been canceled. Canceling this event will prevent the left click from being registered, preventing block breaking (although not in creative mode). If the event is canceled, a specific result of success, fail or pass can be provided. By default, the result is pass.

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

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

• IEventCancelable
• PlayerInteract
• [IHasCancellationResult] (no doc page so far)

The following information can be retrieved from the event:

ZenGetter	ZenSetter	Type
ZenGetter hitvector	ZenSetter ​	Type IVector3d
ZenGetter useblock	ZenSetter useblock	Type string ("allow" / "deny" / "default")
ZenGetter useitem	ZenSetter useitem	Type string ("allow" / "deny" / "default")

The following information can be retrieved from the event:

ZenGetter	ZenSetter	Type
ZenGetter cancellationResult	ZenSetter cancellationResult	Type string ("success" / "pass" / "fail")
ZenGetter world	ZenSetter ​	Type IWorld
ZenGetter blockState	ZenSetter ​	Type IBlockState
ZenGetter block	ZenSetter ​	Type IBlock
ZenGetter face	ZenSetter ​	Type IFacing
ZenGetter item	ZenSetter ​	Type IItemStack
ZenGetter dimension	ZenSetter ​	Type int
ZenGetter hand	ZenSetter ​	Type string
ZenGetter player	ZenSetter ​	Type IPlayer
ZenGetter canceled	ZenSetter canceled	Type bool

ZenMethods

• event.damageItem(int amount) damages the item by the specified amount
• event.cancel(); Method, returns void (nothing). Can cancel the event and stop something from happening

ZenGetter	ZenSetter	Type
ZenGetter player	ZenSetter ​	Type IPlayer
ZenGetter position	ZenSetter ​	Type IBlockPos
ZenGetter x	ZenSetter ​	Type int
ZenGetter y	ZenSetter ​	Type int
ZenGetter z	ZenSetter ​	Type int
ZenGetter entityLivingBase	ZenSetter ​	Type IEntityLivingBase