Turmoil/Boost calculations
This page explains how the game calculates the overall bonuses given by the Turmoil curse.
Note that the floor function means to round down to the next integer.
For Attack and Defence:
For Strength:
The resulting values are percentages and can then be multiplied by the user's skill level in order to find the effective skill level.
Example
A player named Elfinlocks challenges a player named Pee Ker XXL at the Duel Arena. Elfinlocks has 76 Attack, 77 Strength, and 75 Defence; Pee Ker XXL has 65 attack, 80 Strength, and 50 Defence. They begin a duel, and Elfinlocks activates Turmoil.
In order to calculate Elfinlocks's total bonus to Attack, the game takes Pee Ker XXL's Attack level (65) and multiplies it by 15% to get 9.75, which is rounded down to 9. Next, the game figures out how much of a percentage increase 9 levels is to Elfinlocks's 76 Attack; it does this by dividing 9 by 76 to get 11.8%, rounded down to 11. The value 11 is added to Turmoil's initial Attack bonus of 15%, giving a total of +26% to Elfinlocks's Attack level. She now hits as accurately as someone with 95 Attack.
The process is the same for Strength and Defence. Turmoil adds 8 levels to Elfinlocks's 77 Strength, which is 10% of her 77 Strength: a total Strength boost of 33%, giving her an effective Strength level of 102. Turmoil adds 7 levels to her 75 Defence, an increase of 9%: a total Defence boost of 24%, giving her an effective Defence level of 93. Overall, her Prayer window reports that her boosts to Attack/Strength/Defence are +26%/+33%/+24%, respectively. Elfinlocks is easily able to defeat her opponent in the duel.