The Grand Spellbook Tower

The effect "①: If you control a Spellcaster monster or there is a Spellcaster monster in your GY, you can activate this effect during your Standby Phase: Choose 1 'Spellbook' Spell Card in your GY, except 'Spellbook Library of the Crescent', and place it on the bottom of the Deck, then draw 1 card" is an effect that creates a Chain Link. (This effect does not target. It can be activated if a face-up Spellcaster monster is in your Monster Zone, or if a Spellcaster monster is in your GY.)

The process of "Choose 1 'Spellbook' Spell Card in your GY, except 'Spellbook Library of the Crescent', and place it on the bottom of the Deck" and the process of "draw 1 card" are treated as occurring simultaneously.

The effect "②: If this card is destroyed by an opponent's card and sent to the Graveyard: You can Special Summon 1 Spellcaster-Type monster from your hand or Deck whose Level is less than or equal to the number of 'Spellbook' Spell Cards in your Graveyard" is an effect that activates in the Graveyard and starts a Chain Link. (It can also be activated during the Damage Step.)

The effect "Special Summon 1 Spellcaster-Type monster from your hand or Deck whose Level is less than or equal to the number of 'Spellbook' Spell Cards in your Graveyard" does not target. When resolving the effect, you choose 1 Spellcaster-Type monster from your hand or Deck whose Level is less than or equal to the number of "Spellbook" Spell Cards in your Graveyard.