3pc T2 threat reduction

(3) Set: Reduces the threat generated by your Scorch, Arcane Missiles, Fireball, and Frostbolt spells.
How does this setbonus actually work?
Is it a specific %based reduction (5 or 10%), or does it reduce threat by a set amount regardless of the damage dealt? And do you gain twice the reduction if you crit?
Mabye more importent, has it been confirmed to actually work on this server?
Thank you
How does this setbonus actually work?
Is it a specific %based reduction (5 or 10%), or does it reduce threat by a set amount regardless of the damage dealt? And do you gain twice the reduction if you crit?
Mabye more importent, has it been confirmed to actually work on this server?
Thank you