How Drop Chances Work in MIR4

A MIR4 monster rolls its drop slots when it dies, and each slot then rolls the item groups attached to it. An item's chance per kill is the slot rate times the group rate, and the drop tool lists that chance for every monster and gathering node that carries the item.

Each monster links to a drop table with up to five slots, named A to E. When the monster dies, every slot fires at the rate stored for it in the table. A slot that fires then rolls its item groups, and each group has its own rate. Multiply the two and you have the chance per kill. The game's Acquisition panel tells you where an item comes from, but it never shows this number. [UC] Soaring Soul Crystal is the plain case: it sits alone in its group, and Giant Goblin's slot C fires on every kill, so every Giant Goblin drops one. The same crystal comes from Ice Demon Warrior at 0.933% and from Goblin at 0.556% per kill, and the tool lists those rates side by side.

Many groups hold more than one item. [R] Snake Pit Demon's Essence shares its group with three other items, and slot C of monsters such as Viperbeast Brute and Viperbeast Crusher fires at 2.083% per kill with that group always rolled. The group lists 12 entries and the Essence fills 5 of them, but the drop tables do not say how one roll picks among the entries. The tool therefore shows the group's chance and each item's share of the entries instead of a percentage per item. A group with a single item gets an exact per-item chance.

Compare the chance per kill across sources first. Each source carries its regions, and the region chip opens the map at that monster, where you can see how many spawn and how far they stand from a waypoint. The item's own page lists the same monsters among its drop sources.