CS Game Terminology - Spell Book

The Spell Book is where you store your Spell, Counterspell, and Resource cards. Keep Spell and Resource cards face up in your Spell Book for all players to see, but hide your Counterspell cards by keeping them face down.
Your Spell Book can hold a maximum of 5 cards at any time (in addition to 1 Companion card if your Character is in Shadow Form). If you have a full Spell Book but wish to Collect a card, simply choose a Spell or Resource card from your Spell Book and move it to the discard pile to free up a space.

Spell cards are found in the Main deck and come in 2 forms: Attack Spell cards and Conversion Spell cards.

Some Spell cards require you to spend a lower level Spell card from your Spell Book as part of their Collection Cost. This is indicated by a gray Spell symbol located in the Collection Cost. If a Spell card's Collection Cost includes a lower level Spell card, you may move any Attack or Conversion Spell card of the appropriate level from your Spell Book to the discard pile to meet that Resource requirement.