So...Veigar made a deal with Kench?
I wonder what the price was for that deal. Implying Kench caught him alone from other Yordles and tempted him for one. Or is it? Yordles naturally have magic now. So maybe Veigar did not make a deal with him. But as speculation sees it, he did.
Veigar probably made a deal to get dark magic at the cost of losing something....maybe his sanity?