You need to find the spellbook before you can learn any spells. It is located in Telefin Grove. If you play as an elf, you start right next to it (and the spell Bolt).
You must have the spellbook equipped (not just in your possession) in order to learn a spell.
You cannot have both a shield and the spellbook equipped at the same time. Furthermore, you can only cast a spell when you have the spellbook equipped. So you have to decide what strategy you want to use for both overall game play and for particular areas or encounters.
To change your active spell, open the (local) map, hit the spellbook button (second from the right on the bottom), swipe from right to left to open the book, keep swiping on the pages until you reach the spell you want active (NB: you have to swipe on the top half of the page where the spell name and icon is or the page will not turn), then hit the green check-mark to select the spell you want. Changing your spell counts as 1 action so it can be dangerous to do if there are enemies nearby. Hence it is good strategy to have the spell you want ready before you get into a dangerous situation.
To cast a spell, tap the spellbook icon to the left of your life and magic meters when it is your turn and there is an appropriate target in front of you.
- Bolt (Magic to Cast: 10)
Location: In Telefin Grove next to where you find the Spellbook. Description: "Cast a bolt down from the heavens to smite your foe. You may not target the innocent. Affects the enemy in the terrain directly in front of you. This spell advances with the player to become more powerful."
NB: Power seems to increase as player increases levels, not as player knowledge increases (however, this is currently an assumption based on playing an elf and putting all skill points into knowledge so a comparison needs to be done to confirm it).
- Missile (Magic to Cast: 7)
Location: Verazoth Tower (North of Telefin Grove) Description: "Zap an enemy with this missile of power. Actually the power is very limited, the Wizard Throzdin, same wizard that made the Magic Mapping Scroll, created the spell. But it's a start! You may not cast this spell at the innocent."
NB: This spell seems to consistently do exactly 7 damage every time. It does not increase in power.
- Fireball (Magic to Cast: 15)
Location: After completing the quest Giant of a Quest and collecting your reward, head to the portal near the King and go through it to travel to the Sneaky Passage of Margus. You will see the Fireball spell on the wall directly in front of you. Description: (When learning spell) "Shoot a fireball at your enemy from a distance. You may not target the innocent." (In Spellbook) "Cast a firey ball, from the Pits of Flame, to smite your foe. You may not target the innocent. Affects the first enemy, in your path, directly in front of you."
NB: This is a ranged spell.
- Ice (Magic to Cast: 15)
Location: Hidden in The Great Library in Norrab Castle near the elf who is looking the Ice Spell. More specifically, if you look at the map of The Great Library, the bookcases spell 'EK' (the game designer's initials) with a crown over the letters. The Ice spell is in the top of the top left corner of the 'E'. Description: "Freeze your enemy. Spell cancels when you attack or leave area. Some enemies will be immune."
- Portal (Magic to Cast: 10)
Location: NecroCrypt Level 3 (one square to the East of Kyre on the world map). It is on the wall behind the necromancer whom you need to kill to complete the Necromancer Quest. Description: "Conjure a gate of the ValKin to return to your last resurrection shrine! It will fail if cast in an area with a person, another teleport or an item. The area in front of you to cast it must be a completely empty area."
NB: Unlike other portals in the game that are permanent, the portal created with this spell disappears when you use it.
PRO TIP: If you want to be able to make a quick exit from an area, cast Portal along your planned escape route before engaging the enemy.
- Heal (Magic to Cast: 25)
Location: A cave painting near the middle bottom of the Crimson Caverns Level 1 area (South of Norrab) Description: (When learning spell) "Use the power of the ValKin to invoke a healing of your wounds!" (In Spellbook) "Heal your wounds! Use the power of the ValKin to evoke a healing of your battle damage. Multiplier of 3 times your current level."
PRO TIP: If you are not a Knowledge (i.e. Magic) heavy build, using Heal will save you time when using a ring to regenerate from severe damage since your Magic will become full long before your Life will.