NOTE: Depending on how you use them, some spells might ruin your reputation/relationships with the classmates/villagers. Use them carefully if you don't want everyone to end up hating you.
The descriptions are the same as they are in the in-game spell list, and the spells are in the order they appear. I take these from other websites and/or my own game.
Magic
Flatulence
Magic-Toilet-Performance
Use this to make whomever it is cast upon to break wind. If it is cast on a ghost, it will be blown away
Metal Basin
Magic-Big-Trick
A metal tub will fall on your target from above. Your target will become dizzy and lose their memory.
Spiderweb
Magic-Slow-Bug
Use this on an insect to temporarily stop it in its tracks.
Sleep
Magic-Daytime-Sleepy
Use this to make your target fall asleep.
Magnetic
Magic-Love-Gather
Use this to force the two it is cast upon to stick together, literally.
Love Insight
Magic-Explore-Sweetheart
Use this to find out who your target loves.
Transformation
Magic-Exchange-Who
Use this to take the form of another classmate.
Party Popper
Magic-Flower-Instrument
Use this to create a lively, vibrant atmosphere.
Cloud Hammock
Magic-Sky-Sleep
Use this to make someone fall asleep on a cloud. Whoever is closest to the person will also fall asleep on a cloud.
NOTE: Actually the description on this one is wrong; it makes you float on a Cloud, sleeping. If an NPC friend is nearby, they will also fall asleep.
Shooting star
Magic-Gather-Star
Wave your staff with good timing to make more shooting stars appear. They will continue to fall for a while.
Treasure Hunt
Magic-Secret-Seek
Use this to make buried treasure glow.
NOTE: It makes treasures in the vicinity glow for a short time, and make a distinctive sound, so you will have to cast it over and over again in different areas to find treasure. "In the vicinity" means within 15 or so paces, not a large distance.
Locations of Treasure: 5 in the Cave, 1 on Island, 1 at Lovers' Point, 1 in the Fungi Forest, and 3 elsewhere in town.
Lightning
Magic-Star-Anger
Use this to zap those guilty of evil deeds. Or piss off your friends.
Incantation
Rainmaking
Incantation-Sun-Sad
On a clear day, transform, say the words, then hold Aquamarine.
NOTE: Makes rain on any day, be it clear or overcast
Rainbow
Incantation-Sun-Happy
Use this on a rainy day to create a rainbow. Transform, say the words, then hold Turquoise.
NOTE: Make the rain cease on a rainy day and makes a rainbow appear.
Flower Rain
Incantation-Flower-Many
Transform in a place where you can find four Marguerites, say the words, then wave your staff.
NOTE: The placement of the flowers should look like this:
XX
XX
with your character standing in the middle.
Star Message
Incantation-Star-Telegram
Transform, say the words, then hold a Shooting Star Silver. It will only take effect the following night.
Friendship
Incantation-All the time-Together
Go to the ruins with someone you wish to befriend, transform, say the words, then hold an Emerald.
Declare Love
Incantation-Contest-Love
Take your love to Lovers' Point at night. When the bell tolls, transform, say the words, then hold a Red Rose.
NOTE: This will greatly increase your love standing with the individual you used it on. However it doesn't automatically make them go steady with you, so it must be used multiple nights in a row (it can only be used once per night)
Sweet Dreams
Incantation-Sleep-Date-[Classmate]
Place a Lapis Lazuli near your bed. At night, transform, say the words, then lie down in bed.
Make Peace
Incantation-Sad-Exchange-Happy
Transform, say the words, hold a Yellow Marguerite, then send your telegram.
NOTE: You send the telegram to the person you want to reconcile with.
Sit by Me
Incantation-Class-Date-[Classmate]
Transform and say the words while in your classroom seat. Hold a White May Lily and invite the one you like to class.
Popularity
Incantation-All-See
At night, go to the ruins, transform, say the words, then hold Rose Dew.
NOTE: Makes you more popular amongst your classmates.
Honor Student
Incantation-Learn-Above
Go to your classroom, transform, say the words, then hold an Amethyst.
Invisibility
Incantation-See-No
Transform, say the words, circle around the ruins once, stand in the middle of the ruins and hold a Crystal.
NOTE: All this allows you to do it evesdrop on conversations, not very useful.
NOTE: While invisible, ghosts won't directly chase you, but if you touch them yourself they'll still warp you.
Mystery Bloom
Incantation-Mystery-Give
Transform, say the words, then water the uniquely-colored flower. Repeat the process for a few days.
Mystery Gate
Incantation-Come-Door
Transform, say the words, place a Black Marguerite on the ground, circle around it, then face north to wave your staff.
Secret Saving
Incantation-Money-Love
Hide money in the ground, say the words, then water it with a watering can.
NOTE: this only works when 1 ritch is buried, and when dug up again, it will only grow to 10 ritch. Not a very useful money maker
Sharp-eared
Incantation-See-Rumor
In your room, face a piece of furniture with a mirror, transform, say the words, then hold a Witch's Claw.
Treasure Hunt
Incantation-Play-Treasure
In the park, transform, say the words, then hold Gold Ore.
NOTE: Makes treasure chests appear in the ground; when you find them, you can open them by holding them.
Lucky
Incantation-Incantation-Incantation
When your clock reads the date of your birthday, transform. Say the words, then wave your staff. Repeat this for a minute.
Mushroom
Incantation-Trick-Mushroom-[Classmate]
Go to Fungi Forest, transform, say the words, then hold a Mushroom.
NOTE: Makes Mushrooms grow in the specified classmates room/house.
Connect Doors
Incantation-Come-Dorm Room
Transform in front of the Gateway of the Beginning and End with the one you like, say the words, then hold Sapphire.
NOTE: Makes the student you brought to the door move into the dorm with you (by connecting a dorm room to the villager's apartment).
Phantasm
For boys:
Incantation-Play-Boy-Toilet
For girls:
Incantation-Play-Girl-Toilet
In front of the toilet stall, transform, say the words, then hold a Red Tulip
NOTE: Makes a Phantasm appear that tells you interesting stuff.
World Tree
Incantation-Greeting-Tree
Transform in front of Fungi Forest, say the words, then enter the forest.
NOTE: The World Tree will appear, and then give you gifts depending on how many weeds you have pulled up, wilting plants watered, etc.
