The PlayerAnvilUpdate Event is fired when a player places items in both the left and right slots of a anvil.

• If the event is canceled, vanilla behavior will not run, and the output will be set to null.
• If the event is not canceled, but the output is not null, it will set the output and not run vanilla behavior.
• if the output is null, and the event is not canceled, vanilla behavior will execute.

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

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

• IEventCancelable

The following information can be retrieved from the event:

ZenGetter	ZenSetter	type	Description
ZenGetter leftItem	ZenSetter ​	type IItemStack	Description The left side of the input.
ZenGetter rightItem	ZenSetter ​	type IItemStack	Description The right side of the input.
ZenGetter outputItem	ZenSetter outputItem	type IItemStack	Description Set this to set the output stack.
ZenGetter itemName	ZenSetter ​	type string	Description The name to set the item, if the user specified one.
ZenGetter xpCost	ZenSetter xpCost	type int	Description The base cost, set this to change it if output != null.
ZenGetter materialCost	ZenSetter materialCost	type int	Description The number of items from the right slot to be consumed during the repair. Leave as 0 to consume the entire stack.

• event.cancel() sets the event as cancelled.