Val had inspected Clea in the past. It was when he first saw him in the lower city. So he knew Clea was a Level 2 mid-rank wizard as well as a Level 3 bloodline user. He was also intimately familiar with Clea's arsenal of skills and runes.
One rune, in particular, piqued Val's interest, and not in a good way.
This particular rune allowed Clea to miraculously dodge death and teleport himself to a safe location. This meant that if Val attempted to land a fatal blow, Clea could potentially escape unharmed.
This was extremely problematic for Val. After all, if Clea managed to slip away, Val's entire plan would be ruined.
Clea was a loyal servant of the second young master of the Thunderspear tribe, none other than Leon. Leon had meticulously plotted the assassination of Oliver. If Clea escaped Val's clutches and reported back to Leon, it would be a headache for Val. The consequences would be dire.