They knew their opponents were strong, but they weren't far off their current level of power. If they regained the help of the sealing formations they had from the start, the tide would shift again towards them.
William wasn't doing this out of impulse. When he spotted the large number of masters coming here in one wave, he knew Lingerie's intentions from doing so.
"She wants to buy herself extra time to fix the portal," there was no other explanation for her to take such a huge cost to send such a large number of masters in one go.
She wanted her masters to take control of the portal zone, causing lots of trouble for William and others, buying herself enough time to repair the portal.
And that also meant another thing; "she is coming in the next wave!"
