The /tick* commands implement dikumud tick counting, similar to tintin. When the ticker is started with /tickon, it will warn you 10 seconds before each tick, and print "TICK" on the tick.
The messages can be changed by redefining the /tick_warn (10-second warning) and /tick_action ("TICK") macros. You can make them perform any tf command, not just printing.
It is up to you to start the ticker in synch with the mud. If the mud prints something on a tick, you can define a trigger on that which calls /tickon.
/Tick displays the time remaining until the next tick.
/Tickoff stops the ticker.
/Tickon and /tickset reset and start the ticker.
/Ticksize sets the tick period to n seconds (the default is 75).
See: /require, timing, prompts