If you deal a small amount of magic dmg (for example a sc with +1-2 cold dmg, or a stone of Jordan with 1-12 lightning dmg) this damage will be reduced by items with Magic Damage reduced. If the traget has say Magic Damage Reduced by 20 (or any number that exceeds the magic damage done by one element. This spare MDR will roll over and be used to reduce the physical damage aswell. Resulting in your sc or SoJ or whatever making you do less damage overall than without it. If you have more than one element this will be applied separately for each element greatly reducing your phys damage if you are unlucky. (which is why vengeance palas are useless in LLD)MDR bugs is mentiond in the build, what is this?
I hope you dont mean them fissure druids who just sit in town and run out and use fissure on you while your dueling someone else lolWindy druids are very fine pub builds and fissure druids can compete with anyone.