When you fill a box (four ticks) on any legacy track, take 2 experience. This experience may be spent when you Advance.
Once you completely fill the tenth box on any legacy track, clear that track. You may start again marking progress on the cleared track, but earn experience at a reduced rate of 1 experience (instead of 2) for each filled progress box. If you make a progress roll against this track, resolve the outcome as if at 10 progress.