The School of Conjuration governs raising the dead and summoning creations from Oblivion. This skill makes it easier to cast these spells, as well as Soul Trap and Bindings.

Conjuration is good for any type of mage since it lets you summon a companion which can always be useful in battles. Any class can complement itself with Conjuration. Also useful for enchanters because of the Soul Trap spell.

Level up conjuration by sending your conjured creatures into battle and having them do damage

TRAINERS
Journeyman Trainer: Runil (Falkreath)
Expert Trainer: Phinis Gestor (College of Winterhold)
Master Trainer: Fallion (Morthal)

SPELLS

Novice:
Bound Sword: Creates a magic sword for 120 seconds. Sheathe it to dispel.
Conjure Familiar: Summons a familiar for 60s wherever the caster is pointing
Raise Zombie: Reanimate a weak dead body to fight for you for 60 seconds

Apprentice:
Bound Battleaxe: Creates a magic battle axe for 120 seconds. Sheathe it to dispel.
Conjure Flame Atronach: Summons a Flame Atronach for 60 seconds wherever the caster is pointing.
Reanimate Corpse:  Reanimate a more powerful dead body to fight for you for 60 seconds
Soul Trap: If target dies within 60 seconds, fills a Soul Gem.

Adept:
Banish Daedra: Weaker summonded Daedra are sent back to Oblivion
Bound Bow: Creates a magic bow for 120 seconds. Sheathe it to dispel
Conjure Frost Atronach: Summons a Frost Atronach for 60 seconds wherever the caster is pointing.
Revenant: Reanimate a powerful dead body to fight for you for 60 seconds

Expert:
Command Daedra: Powerful summoned and raised creatures are put under your control
Conjure Dremola Lord: Summons a Dremora Lord for 60 seconds wherever the caster is pointing
Conjure Storm Atronach: Summons a Storm Atronach for 60 seconds wherever the caster is pointing
Dread Zombie: Reanimate a very powerful dead body to fight for you for 60 seconds
Expel Daedra: Powerful summoned Daedra creatures are sent back to Oblivion

Master:
Dead Thrall: Reanimate a dead body to permanently fight for you. Only works on people.
Flame Thrall: Summons a Flame Atronach Permanently
Frost Thrall: Summons a Frost Atronach Permanently
Storm Thrall: Summons a Storm Atronach Permanently

PERKS

Novice Conjuration
Cast Novice level Conjuration Spells for half Magicka

Apprentice Conjuration
Cast Apprentice level Conjuration spells for half Magicka
Requires: Novice Conjuration, Conjuration 25

Adept Conjuration
Cast Adept level Conjuration spells for half Magicka
Requires: Apprentice Conjuration, Conjuration 50

Expert conjuration
Cast Expert level Conjuration spells for half Magicka
Requires: Adept Conjuration, Conjuration 75

Master Conjuration
Cast Master level Conjuration spells for half Magicka
Requires: Expert Conjuration, Conjuration 100

Note: Novice, Apprentice, Adept, Expert and Master Conjuration are a MUST for  anyone planning to use spells from the Conjuration tree, otherwise you will not have enough Magicka to cast your spells.

Mystic Binding
Bound Weapons do more damage
Requires: Novice Conjuration, conjuration 20

Note: If you use bound weapons, take this perk

Soul Stealer
Bound weapons cast Soul Trap on targets
Requires: Mystic Binding, Conjuration 30

Note: Good skill to have if you use Bound Weapons, you can easily fill soul gems for enchanting and recharging

Oblivion Binding
Bound weapons will banish summoned creatures and turn raised ones
Requires: Soul Stealer, Conjuration 50

Note: Take this skill if you use bound Weapons as it will help you a lot against summoned and raised creatures

Conjuration Dual Casting
Dual casting a Conjuration spell overcharges the spell, allowing it to last longer.
Requires: Novice Conjuration, Conjuration 20

To dual cast a spell, arm it in both hands and hold both buttons to cast it.

Necromancy
Greater duration for reanimated undead
Requires: Novice Conjuration, Conjuration 40

Dark Souls
Reanimated undead have 100 points more health
Requires: Necromancy, Conjuration 70

Summoner (1/2)
Can Summon Atronachs or raise undead twice/three times as far away.
Requirements: Novice Conjuration, Conjuration 30/70

Atromancy
Double duration for conjured Atronachs
Requirements: Summoner, Conjuration 40

Elemental Potency
Conjured Atronachs are 50% more powerful
Requires: Atromancy, Conjuration 80

Note: Take this when you can, as it significantly increases the power of your Atronachs

Twin Souls
You can have two Atronachs or reanimated zombies
Requirements:  Dead Souls or Elemental Potency, Conjuration 100

Note: Very powerful perk, lets you have one more summoned or raised creature.