Xerath changes Source:

• Base mana reduced from 459 to 400
• P cooldown is now reduced by 2 seconds per kill
• R missiles increased from 3 - 5 to 3 - 7
• R base damage reduced from 200 - 300 to 200 - 280
• R AP ratio reduced from 45% to 40%

In the Comments:

• R missiles now does 20/25/30 +5% AP more damage per champion hit with a previous missile.