Stars

Star Summoning is a type of magic where the user summons stars and representations of the sixteen constellations by opening their gates through the use of magical items.

White Stars:

Can be summoned with easy to buy magic items
Total number unknown
Appear in humanoid or animal form

Warm Stars:

Can only be summoned with certain cards
The cards have one of these colors: red, orange, yellow
Only ten known
Often appear in humanoid form

Cold Stars:

Can only be summoned with special keys
There are four of them
The keys have one of four colors: pink, purple, blue, green
If all four keys are found and are summoned at the same time, they become one entity
Appear in humanoid forms

Colorful stars:

The Sixteen Zodiac Signs
Can only be summoned with certain spells
Appear in humanoid or animal form, whatever situation it's appropriate