I've been on both ends of this. Played a match where I was mid as Zed vs a Katarina and once I reached lvl 3 and had my w,e,q combo I could almost kill her because I would do about 60% dmg with the combo then thunderlords would come in and boom she's been hit with almost 90% of her health in dmg. This wasn't just early game it continued through mid game where it finally fell out a bit at late game. So the thing is, thunderlords right now is doing a bit too much dmg to squishy champs consistently and is pressuring their lanning phase too hard. I propose the early scaling's on thunderlords get nerfed a bit to better balance out lanning phases between assassins and mages.