Evolution

[You have fused with a Tier 4 Rare core]

And just after this notification, another one pops up in front of him..

[Your exclusive attribute had bloomed.]

[You have received the attribute…]

The long awaiten exclusive attribute had finally bloomed, but before he could even read the name of the ability, a searing pain began to run all over his body.

The energy within the core was so great that he felt like his body had melted from the inside. Despite trying so hard, a cry of pain left his mouth.

"Aggggggggghhhhhh!"

He began to notice a strange energy flowing inside his body. The energy from the core is so immense that he could feel his organ exploding. 

The process of organs exploding was fast, but not fast enough to result in instant death. But he couldn't have been so lucky if core had even 5% more energy within it.