if the bearer of this item is attack it increases the magic reduction given to the hero.Up to 10 stacks.When it reaches it stacks it releases a burst that reduce magic reduction to nearby units.reduced Magic Reduction is also increases per second.As long as the targets is within the AoE of the carrier then the magic reduction is continue to affect until it reaches its limit of reduction.If the target is not inside the AoE then the effect will be gone by backing it to its state (For example.The unit is affected by the effect RMR stack count is (1,2,3,4,5) but it he moves away at 6 so the RMR will fade at this time (5,4,3,2,1 then the RMR will be removed from the target.
ANOTHER INFO.
If the target is not on the AoE and the hero decide to move near the target then the effect will be increase again.
TARGET IS AFFECTED
RMR (1,2,3,4,5,6)
TARGET IS MOVING AWAY
RMR (6,5,4,3) (NOTE THE EFFECT STARTS FADING AND STOP AT 3)
TARGET IS AFFECTED AGAIN
RMR (3,4,5,6,7)
THE MAGIC REDUCTION STACKUP starts again after the RMR stops.
You can add or maybe i can add more details in it.