XP Item charged token

#1
At the creation of a new character, like the bind stone, you get an <experience gem>.
This gem is non tradable, not storable to account vault, non vendorable either.

The gem contains 25 charges.
Each time a charge is used, the character receive a buff for 60 minutes that will apply the following bonus to his experience:
10 x (26- ChargesLeftOnExperienceGem)
So first time use, you are worth 10% xp for you and or your group. When your stone has only 10 charges left, you use it and are worth 150% and on last charge 240%.

This could be cumulative with instance bonuses with a cap of 250% at all time for a character. With a cap of 1000% for the group.

This will be new player friendly, this will be solo friendly, this will be awesome in group, this will lessen the "instance bonus requirement".

Later on, this could be a rare gem one could loot ONLY in epic raid with say 5 charges only and account vault tradable, giving a character 5 hours to xp at 200% or more if in a group.

This would be an opportunity to lower the mob body type and push people in groups rather than on camps.

Hope you like it and as usual, if there is a downside that I missed, use kind words to enlighten me rather than being a dick.