Mythic Rift
A rift of 100 tiers with enemies at level 70, open only on Inferno. It is entered from The Brave Memorial in the City of Veldak, which is unlocked for 1,000,000 gold at level 70 on Inferno. Each tier makes enemies stronger and raises the gold and experience.
Entry cost
Entering needs one of each in the inventory. They are used up only when the run is completed; leaving or dying costs nothing, and the next tier or a rerun needs a new set.
Who drops them
Tiers
The entrance lists tiers 1 to 100. Tier 1 is open from the start; for Singleplayer characters, completing a run opens the next tier, up to tier 100. The rift needs Inferno to be the current difficulty.
A run
A run has 9 regular encounters and a boss encounter. 4 to 6 enemy types are drawn for the run from the rift's enemy list. Each regular encounter draws a number from 40 to 50 and is filled with one enemy of each drawn type, then more of them at random, until their rift sizes (1, 2 or 3, on each enemy's page) add up to that number, never above 50. The boss encounter is filled the same way, plus the boss from the boss list. The first encounter starts 3 seconds after the run begins and each next one 3.5 to 4.5 seconds (at random) after the last enemy dies. The rift has no elite encounters. For online characters, values planned by the game server replace these.