Collatz modifiers is simply a stat that changes on use semi-randomly until it decays, using the Collatz conjecture.
example: a sword has 7 damage(collatz modifier).
1.each time the sword hits, collatz procedure is applied:
if the number(damage) is odd, multiply by 3 and add 1, otherwise divide by 2.
The sword damage will be 7,22,11,34,17,52,26,13,40,20,10,5,16,8,4,2,1 for the series of hits.
2.After the collatz sequence reaches 1, the modifier is reset back to default value (7 in this case).
Deterministic randomness in modifiers.
Easy to calculate for in-game formulas.