Link to the reasoning behind this rule

Declare the race and subrace you intend to play before rolling your attributes. Also declare your class.

You then roll 4d6 dropping the lowest result and adding up the highest three each time, for 6 times.

You check if you can get at least a +3 or higher applicable to the attribute most needed by the class you declared, a +2 or higher for a secondary attribute, and a -1 or lower modifier with the 6 resulting numbers after also applying the racial modifiers for the race and subrace you declared.

You may choose to have your +3 or higher and/or +2 or higher in an attribute that is not your class’ most needed one, although this is not recommended as it goes against the purpose of this homebrew rule.

If you get at least a +3 and a +2 but you are lacking a negative modifier, you can lower one of your scores below 10. However, if you are lacking a +3 or +2, you cannot take one of your scores and increase it: if you don’t have the requirements, you reroll all of your attributes and start again.

You may choose to lower any amount of scores you wish as long as you keep the +3 or higher and +2 or higher.