Loot and rarity

One roll per wave

When the last enemy of a wave dies, the game rolls that wave's loot once, at that enemy's level. Killing ten wolves instead of three changes nothing about the item roll; clearing waves faster does. A normal wave gets one item roll, a mini-boss two and a zone boss three, and each roll tries for a divine item first, then picks a rarity.

The rarity table

Each wave type has two rarity tables, one for level 1 and one for level 70, and the game slides between them by enemy level. For a normal wave the chance of getting nothing at all rises from 87.4% at level 1 to 95% at level 70, commons fall, and legendaries appear from level 10 and reach 0.15% per roll at 70. A zone boss at level 70 rolls legendary 3% of the time, three times over. That is why a stage's single boss wave is worth more than all the normal waves before it put together.

What Magic Find does

Magic Find multiplies the uncommon, rare and legendary weights, not the final chance. With +100% Magic Find those three weights double while "nothing" and common stay put, so a legendary on a level 70 boss goes from 3% to 3.7% rather than to 6%. The gain is closest to double where "nothing" dominates the table, which is normal waves. Magic Find also counts at 30% toward the divine roll and at 20% toward rune rarity.

Nightmare and Inferno add a second multiplier on the same three weights: 0.5% per map level on Nightmare and 1% on Inferno, where map level is the level the stage had on Normal. A boss on the last stage of the game on Inferno rolls legendary 3.6% of the time. Early stages give almost no bonus on the harder difficulties even though their enemies are level 70 too, so farm late maps.

Which item you get

Once the rarity is set, the game picks a slot first and an item second. Every slot that has at least one item you can use at that level is equally likely, except Back, which is 7% as likely as the rest. Then it picks evenly among the eligible items in that slot. A slot with two legendaries therefore gives each of them better odds than a slot with eight. The drop rate calculator does this sum for any single item.

Divine, ancient and Black Mist

Divine items only drop from level 70 enemies on Inferno, from a separate roll before the rarity roll. The base chance is 0.001% per roll on a zone boss and 0.0003% on an elite wave; normal waves have none. Divine items come with fixed stats at item level 990.

A legendary from a level 70 enemy can also turn into something better. On Nightmare and Inferno 0.25% of them arrive as Black Mist: unrevealed, item level 850, and you choose each affix from two offered stats, all at their maximum roll. If it is not Black Mist, it has a 10% chance to be Ancient, on any difficulty, with every affix at its maximum. In practice about 10% of endgame legendaries are ancient. Back slot items never get either.

Solo Self-Found

Offline characters carry the Solo Self-Found status, and it multiplies the odds of the rarest drops by 2. That covers the divine roll, Black Mist (0.5% instead of 0.25%), the Legendary and Set weights of the boss rune roll, and any enemy or Rift special drop that is a Legendary Rein, a Legendary or Set rune, divine gear, a Gold Bar or a Consecration Stone. Super-rare fish get the same boost. Online characters keep the normal odds. The boosted items are exactly the ones online characters can trade.

Everything else in a wave

Gems roll separately at 1% per normal wave, 6% per elite wave and 12% per boss, ignoring Magic Find, and only from level 30. Runes only come from bosses at level 40 or higher, 2% per boss kill, and set runes need Inferno. Every wave also has a 0.05% chance to drop a treasure map key for the difficulty you are on.

Enemy special drops, which include every minion's Rein and the boss upgrade materials, follow different rules: each distinct enemy type in a cleared wave rolls its own list once, whatever the number of copies. They never roll in the Mythic Rift. Each enemy page lists its drops and their chances.