I’m using a non-official translated version (there is no official one for my language) of the 5e PHB, and checking it with the official one makes me confused.
When you roll damage for a spell, you can spend 1 sorcery point to reroll a number of the damage dice up to your Charisma modifier (minimum of one). You must use the new rolls.
In a practical way, how does it work?
Can I reroll the number of dice up to my Charisma modifier, or only the dice which are lower than my charisma modifier?
Building a scenario
I have a Cha MOD of 5.
I have the following roll:
3d6: 1, 2, 3;
3d8: 4, 5, 7;
2d12: 6, 7;
Empowered Spell allows you to reroll a number of dice; it does not make any specification on the value of the dice.
When you roll damage for a spell, you can spend 1 sorcery point to reroll a number of the damage dice up to your Charisma modifier (minimum of one). You must use the new rolls.
Compare to Great Weapon Fighting, which explicitly calls out the values you get to reroll.
When you roll a 1 or 2 on a damage die for an attack you make with a melee weapon that you are wielding with two hands, you can reroll the die and must use the new roll, even if the new roll is a 1 or a 2.