code:

on *:join:#: {
  inc %joincounter
}


on *:join:#blitzuk: {
  msg $chan 3 ((welcome 4 back 3 to 4 #blitzuk 3 $nick || 4 i 3 have 4 seen 3 %joincounter 4 joins! ))
}


try that then :
on *:join:#blitzuk:{ 
inc %joincounter
msg $chan Welcome back to $chan $+ , $nick || i have seen %joincounter joins
}