if you want a really accurate method, I recommend the -z flag, because using -u3 will constantly reset the Unset-Timer each time its called... allowing the data to never expire. (eg, if someone uses your !trigger precisely once every 2 seconds, after 4 tries in 8 seconds, he would be ignored)
Using the -z flag method takes a bit of math. In your case, it's relatively easy, the user is allowed 1 line per 1 second.
/inc -z %TriggerFlood 1
if ( %TriggerFlood > 3 ) set -z %TriggerIgnore 60
If ( %TriggerIgnore ) return (ending your script)
You can reference %TriggerIgnore to see how many seconds are left on the ignore. Alternately, you can set -u60 %TriggerIgnore $true