In the latest AMA, Devs dropped Doctor Blight's statistics. He's definitely an insane monster, a card that you want to keep forever! Let's analyze quickly his stats.
A neutral monster
Mana cost: 4
Speed: 1
Health (Level1): 3
Abilities (Level1): Affliction + Slow
Wow! 4 mana cost with slow and affliction is like having Ooze (Mana 1) and Captain Ghost (Mana 7) in 1 card. Will save a lot of Mana and slot if you have this.
Now look at the highest level abilities.
Affliction + Slow + Poison + Scavenger + Weaken
This is ultimate debuff!!
Let's see if Devs will make additional adjustments before the Official Release.