I know it's early and it's only PBE but..
Some of these masteries have me really concerned about the power initiators are going to have. Many of them are naturally tanky and that's fine, I'm not too concerned about them getting a bit more tanky with shields, etc. But many of these tanks, Nautilus and Malphite as two examples, put out disgusting levels of damage without any real damage items - especially Malphite considering his armor scaling damage. Please tell me you'll plan on retuning many of these tanks damage down because I really don't want to go back to that garbage tank meta we had this season. That was legitimately the most unfun time I've ever had playing league of legends in 5 years of playing.