Weighted

Weighted refers to the way spells/items/abilities select targets. Any spell/item/ability (with the notable exception of one unique that avoids targeting the top stack) that is described as targeting a random stack(s) will prefer to target the largest stack(s) by NP instead (usually but not always the top stack(s)).

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See also: http://wiki.the-reincarnation.org/index.php/Random_stack

The game code chooses a stack by giving the top stack a 50% chance of being selected, and then halving the chances after that until you are out of stacks.

"Random" stack selection

Stack #	Chance of selection
1 (aka top)	50%
2	25%
3	12.5%
4	6.25%
5	3.12%
6	1.56%
7	0.78%
8	0.39%
9	0.19%
10	0.01%