Achievements can be found under the Collections tab, these will boost your Energy/EN and Battle Points/BP recovery time, as well as award extra gold or xp.

Type Reward Conditions
C Collector Energy recovery time shortened by ? seconds Monsters of C, C+ rank found
B Collector Battle Point recovery time reduced by ? seconds Monsters of B, B+ rank found
A Collector Gain ? Gold per day Monsters of A, A+ rank found
Summoner Gain ? bonus Ally Points per day Monsters Summoned
Sacrificer Sacrifice cost reduced by % Monsters Sacrificed
Skill Collector EXP from sacrifices increased by % Skills found. Each Skill level counts as 1

Combo Collector

Awards Items when completed Combos found
Explorer Awards Gold when completed Quest Areas completed
Adventurer Awards items when completed Player Levels reached
Warrior Earn ? more EXP from battles Earned Honor Points