Creature Mastery

A creature's masterylevel tells you which level the next summoned creature of that creature type will have. If you raise a creatures mastery level you will no longer be able to summon this creature of a lower level. Once you advanced the mastery of a creature the mastery progress will be reset to one.

NOTE: You can only summon one of the next level creature until you find more.

What does raising the mastery level do to the creature?

It drastically increases the stats of the given creature.

It increases the cost of summoning the creature.

What does it do to the dungeon?

It affects the tier which your dungeon belongs to.

"Dungeon Tier" is equal to "Level of the highest creature in your dungeon"