The WorldTick Event is fired each tick for each world on both client and server.

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

Event interface extensions

Link to event-interface-extensions

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

ZenGetters/ZenSetters

Link to zengetterszensetters

The following additional information can be retrieved from the event:

ZenGetterZenSetterType
ZenGetter
world
ZenSetter
Type
IWorld

ZenGetters/ZenSetters/ZenMethods from extensions

Link to zengetterszensetterszenmethods-from-extensions

The following information can be retrieved from the event:

ZenGetterZenSetterType
ZenGetter
phase
ZenSetter
Type
string with value of STARTor END
ZenGetter
side
ZenSetter
Type
string with value of CLIENTor SERVER