Thresh seem to be buged still

Long story short i had a game where i went ap thresh and my ult would do ruffly 900 damage with 23 magic pen. go against a ziggs with only 43 magic resist, I ulted and didn't look like he had moved a bar of health with him hitting it twice. Other abilities don't seem to be doing that much damage also with the build i had. Build--->Luden's Echo, Zhonya's Hourglass, Sorcerer's Shoes, Rabadon's Deathcap, Catalst the Protector(all i got to) Runes---> Ability Power Quintessences, Magic Pen. Marks, Armor Seals, and Magic Resist Glyphs Masteries--->12/18/0

Also I've been noticing souls flying to be from places i haven't even come close to.