new fiddlesticks passive.

Dread [ Passive ] Aura removed; now, every spell and basic attack decreases the target’s magic resistance by 10 for 3 seconds

does anyone know if it stacks? if so is there a cap? is the timer refreshed upon applying more stacks or do your initial stacks time out after 3 seconds?

reason being, wits end/nashors/rageblade might be a thing with fiddlesticks now?