A Sixth Rank Transcendent Being already possessed the strength to slaughter cities and annihilate nations.
The Cursed Earth deployed by the Desolation Plague Monster was a spell-like ability it naturally mastered. If this powerful spell was fully expanded, the area it covered could reach several tens of square kilometers, producing up to six different random curse effects simultaneously within such an extensive range.
Such a powerful spell could not possibly be ready in a short time; the entire spell's channeling time took as long as ten minutes. However, a characteristic of a spell-like ability is that it does not require gestures or verbal components, and can be released merely through thought. During the previous "lesson," the Desolation Plague Monster had been quietly channeling this spell. Now that the confrontation was inevitable, the spell was immediately released, as simple as pulling a trigger.