The EntityLivingDeathDrops Event is fired whenver an Entity's death causes dropped items to appear.
It can be canceled to stop the entity from dropping anything.

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

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

• ILivingEvent
• IEventCancelable

The following information can be retrieved from the event:

ZenGetter	Return Type
ZenGetter drops	Return Type List<IEntityItem>
ZenGetter damageSource	Return Type IDamageSource
ZenGetter isRecentlyHit	Return Type bool
ZenGetter lootingLevel	Return Type int

You can either add to the droplist or completely substitute it with a new one:

ZenScript
 Copy
event.drops = //reference to IEntityItem list.

//event.addItem(IItemStack item);
event.addItem(<minecraft:iron_ingot>);

//event.addItem(IEntityItem iten);
event.addItem(<minecraft:iron_ingot>.createEntityItem(event.player.world, event.player.position));