The best daily quest to buy attempts for is Icaria. Icaria will drop feathers which will massively boost CP and performance in PVE/PVP

This is the best use of your diamonds. MOST of these items will massively boost CP and performance in PVE/PVE!

These are a nice addition and cp boost to your character. If on a budget do not buy rings first, instead go for event items which will help more in the long run!

These are a good use for diamonds to level up quicker. They will boost xp by 50%, check stats to see current xp buff.