Two Warband Mentors: The War Within

[spell=430191] is part of a stacking achievement for your alts. You'll get additional 5% experience up to five times.

1. 
   
2. One Warband Mentor: The War Within: +5%
3. 
   
4. Two Warband Mentors: The War Within: +10%
5. 
   
6. Three Warband Mentors: The War Within: +15%
7. 
   
8. Four Warband Mentors: The War Within: +20%
9. 
   
10. Five Warband Mentors: The War Within: +25%
11. 
    

This buff is for all characters below level 80 on your account, not just level 70+. Also, if you have multiple WoW accounts under the same battle net account, characters on other accounts that have not upgraded to The War Within expansion don't seem to get this bonus.