The Tale of Tamiyo

When the first, second, or third chapter ability of The Tale of Tamiyo resolves, the ability will continue until you mill a set of two cards that share no card types or you mill one or fewer cards. You can't just pause the story whenever you want to. (And why would you? It's quite the story.)

Because you're paying the spells' costs, if one of the copied spells has {X} in its mana cost, you may choose its value as normal.

The card types in Magic include artifact, battle, creature, enchantment, instant, kindred, land, planeswalker, and sorcery. Legendary, basic, and snow are supertypes, not card types; Horror and Room are subtypes, not card types.

You cast the copies while the last chapter ability of The Tale of Tamiyo is resolving and still on the stack. You can't wait to cast them later in the turn.

If you don't want to cast some (or all) of the copies, you may choose not to. Any copies that you didn't cast cease to exist the next time state-based actions are checked.