Each number on a die roll can result in different abilities, depending on what tome you have equipped. Note that your enemy also has access to these effects. Take note of Attack Up and Dice Up abilities. Attack Up increases damage moderately, and it stacks. If your enemy rolls two of them, always reroll. Dice Up adds one to the enemy's total roll, which may cancel out your attack if you end up winning the roll by a small amount.
Gems
Sell unwanted items to get gems. Make sure you take the time to sell at the items window before you enter a shop. Once you visit a shop, it will disappear afterwards.
Medic set
The Medic set is very useful early in the game. Its passive ability heals you slightly after you end a turn without rerolling. Multiple pieces equipped will not increase its effect. One piece is enough to get maximum healing.
Rerolls
When your enemy has a dangerous roll lined up, for example two active abilities, consider spending energy to reroll. You can regain the energy a small bit at a time with each enemy defeated.
Special map locations
Occasionally chests and exclamation marks will appear on the map. Chest levels give you a chance to find new items. Exclamation mark levels give you stat boosts. These levels are similar to regular chest levels, however there are only three tiers. Reach the last tier to earn four gems. Explore the entire map before progressing so you do not miss any of the special locations.
Stat boosts
Defeat all monsters encountered. They will occasionally drop stat boosts. Having a source of healing over time is important when doing this.
Dice abilities...