The dossier may have mentioned his inherent ability to manipulate drugs in his system, and that implied smarts, especially when it came to creating drugs that effect himself and others.

But damn, was Kray one stupid Goblin. 

Stalker watched from the shadows as his double was lifted and punched through the doorway, and let his smile grow wider. The clone dissembled once it reached the shadows. Purpose served.

That purpose was to draw Kray out, but he hadn't expected the goblin to double in size and weight.

Unraveling the Light, he swung it back and forth. 

Blow...Bang...

The rune allowed him to send out an explosive blast of energy. He had used it earlier against Kray and it was avoided. This time, the case would be different. Kray had effectively come to him.

Rolling to the side, keeping himself on the move, Stalker activated the rune - at fairly close range - and sent the shot directly at the upper body of Kray. 

His opponent had made himself into a nearly impossible to miss target, with his mass doubling as it did. The shot, should it land would explode square on the collarbone and up the neck. Significant damage was expected.