When playing in Crawl Mode, a player may spend Skulls to upgrade their Shuffle Scrolls. However, the functionality you get does not change how they shuffle! The Warrior Scroll activates its bonus only when you use it to shuffle the row. But the other Shuffle Scrolls confer a permanent effect once per turn. They are related to the Shuffle Scroll only in that you must click on the Scroll to see what the ongoing effect is.

Or you can look them up in this post!

The following info is up to date as of version 2.1.0 in the January 20 2019 update.

Ninja scroll:
Level 1: ongoing: if at least 1 ninja is played, +1 blood -1 gold
Level 2: ongoing: if at least 1 ninja is played, +2 blood -2 gold
Level 3: ongoing: if at least 1 ninja is played, +2 blood

Warrior scroll:
Level 1: bonus: if a warrior is played, +1 blood and take 1 dmg
Level 2: bonus: if a warrior is played, +2 blood and take 2 dmg
Level 3: bonus: if a warrior is played, +3 blood and take 3 dmg

Mouse scroll:
Level 1: ongoing: if at least 2 mice are played: +1 blood
Level 2: ongoing: if at least 2 mice are played: +1 gold +1 blood
Level 3: ongoing: if at least 2 mice are played: +2 blood +1 blood

Pirate scroll:
Level 1: ongoing: if at least 2 pirates are played: +1 gold
Level 2: ongoing: if at least 2 pirates are played: +1 gold +1 blood
Level 3: ongoing: if at least 2 pirates are played: +2 gold +1 blood

Holy scroll:
Level 1: ongoing: if at least 1 holy unit is played, -1 blood and heal 1 dmg
Level 2: ongoing: if at least 1 holy unit is played, -1 blood and heal 2 dmg
Level 3: ongoing: if at least 1 holy unit is played, heal 2 dmg

Dwarf scroll:
Level 1: ongoing: add a charge each time a dwarf is played. 7 charges gives a potion
Level 2: ongoing: add a charge each time a dwarf is played. 5 charges gives a potion
Level 3: ongoing: add a charge each time a dwarf is played. 3 charges gives a potion

There are currently no scrolls for Soldier, Worker, Elf, Antihero, Sorcerer, Vagabond, or Monster.