Ultimate Stages (formerly Soulmaster battles) are special battles designed mainly for high level players. One or two Ultimate stages are usually part of the events of each week, open from 22:00 on Friday until Sunday. The bosses of these levels will always drop their card. Some Ultimate stages have been added to the Lost Relic Pass Registry permanently, while others may appear for a limited time during events.
Nightmare is a difficulty introduced with the Power Release of some Sealed Lords, and the Ultimate Greek Lords. These battles are designed for even higher level players. The bosses of these levels will always drop their card. The battle with the related PR material (if applicable) is also a guaranteed drop.
Terror Stages are a variant of difficulty that appears as a separate stage from the Ultimate difficulty, providing an additional diamond for the first clearance. Similar to Ultimate and Nightmare stages, the relevant bosses will always drop their card, but unlike Ultimate and Nightmare stages, the boss will appear in the second-last wave of the battle; the final wave is instead the PR material for the boss, which is also a guaranteed drop.