Champion Point Mechanics
The Champion System is quite complex and after the Orsinium DLC and Patch 2.2 the system is being tweaked further. This page will also be updated as we get more information from the PTS.
For more information on the Champion System as a whole visit the Champion System page.
Champion Points Cap
There will be a cap placed on allocated Champion Points after 2.2 and this will initially be set at 501 CP. What this means is that you can only allocate 501 Champion Points into the passives. Once you have allocated 501 Points then any remaining Points can not be used and are basically worthless. In the future, however, the cap may be raised and you will be able to assign more your Champion Points.
Champion Points XP
The amount of XP that you need to gain a Champion Point is also changing in 2.2 and will actually scale upwards as you get more and more Points.
Your first Champion Point ever will cost around 33,000 XP.
Your tenth CP will cost 42,894 XP.
Your hundredth CP will cost 140,946 XP.
This is similar to a traditional levelling system where it gets harder to level as you get more powerful.
The formula to calculate how much XP is required for any Champion Point is as follows.
((YourTotalPoints / (Cap ^ 0.95)) + 0.08) * 400000
NOTE: If you are above the cap (which is 501 at the moment) then the XP required is also tripled.
Enlightenment will still work after 2.2 and it will still allow you to get 400,000 XP towards a Champion Point in 1/4 of the time. This is a bit confusing, but basically if you are Enlightened you will get 400K XP towards a Champion Point with only 100K actual XP gained.
Full Champion Point XP Table
A full table with the XP required to any Champion Point is available with this spreadsheet created by Domonoid73 over on Reddit.