According to Bechard's fragmented memories, what action did the obyriths take before migrating to the Abyss?

Here's what the lore says, drawn directly from the indexed sources:

Obyrith > Obyrith > Escape to the Abyss The obyriths were not unaware of their limited amount of time, and one of them, purportedly Pazuzu, had hatched an idea on how they could preserve themselves. The obyriths would create a shard of ultimate evil, an object powerful enough to breach the barriers between reality. After pushing past the confines of the cosmos, the shard would serve as an entryway, a seed of evil that they could use to corrupt the most powerful entities in this realm before coming through themselves while leaving their dying world behind. Once they bent their pawns to their…

Source: Obyrith
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