The very first thing Alex did in the area was take away all the Sunhearts and beast cores. If he spent any more time not doing so, he could start infecting the beast cores, making for a potential waste.
He got what he could, but sadly enough time had passed that some of the beast cores had been infected already. A total of 17 Sunhearts had transferred their energy into the beast core, slowly converting it from the inside.
The energy incubated whatever spirit was within the core, slowly turning it into that Sunwraith.
Alex looked at the several infected beast cores and frowned.
While he wanted to take them all with him, it was true that they would all finish incubating at the same time. He would have to consume all of that before it got to that point, which meant consuming all 17 of those beast cores within the next 5 days.
A single such beast core usually helped him cultivate for over a week. It was reckless and incredibly wasteful to do what he wanted to do.