Treat me like I'm a moron

I'm getting back into league after almost a year and a half off. I stopped playing just after the new runes rolled out. Can my fellow Summoners (are we still called that) get me up to speed on what I missed? New champs? Major reworks? Huge buffs or nerfs? Meta changes? How are my tanks holding up? (Rammus4evr)

If you think it's been an important change in the last 18 months, fill me in. Thanks!