12/27/2012 10:40 PMFrom that it seems the bonus item drop is directly dependent on the normal mob item drops. There's also no mention of some mobs not triggering the bonus drop, or the "30% chance of your % chance for a bonus item based on MP". I admit I haven't really tested the drop much, so I imagine you have some experience in the matter as the basis for the posted info.
Posted by Loroese
Lyr posted in the forums about white mobs having an average 30% chance to drop 'something' which triggers an item drop. The original drop does not have to be an item for bonus items to trigger, it can be a tome, or a potions, or a pile of gold, and you will get a bonus item chance.
The 'big guys' not dropping bonus items is from testing in MP10. They drop 2x piles of gold and no items almost every time. This is impossible with 100% bonus items, unless bonus items cannot be a 'third drop'. Any mobs that can drop 2x items normally, therefore will not drop a bonus item in this case.
Thats why heralds are so good, they have a 100% 'something' drop rate, they then have a 10-15% chance of a second drop. When this double drop happens, you dont get your bonus item, but the other 85-90% of the time in MP10 they will always drop an item.
So you'll see 2 items, item and gold, item and potion/tome, or occasional 2 piles of gold (instead of 2 piles of gold and a bonus item).
Tremors and golgors/malechors however have a 100% chance of 2 drops, most commonly 2 piles of gold. They will never drop a bonus item.