I remember ad carries were mid lane

Dragon used to spawn at the same time as everything else, in the beta. There were lots and lots of level 1 5v5s at dragon until they changed that~

Someone mentioned Corki's Phosphorous Bomb used to reveal wards, but it also would blind people it hit.

fiddlesticks used to be viable

Gangplank used to be able to deny.

I'm Larias.

Veigar used to have OPest passive in game (steal 20% AP of champs within 900 range of you)

You used to be able to detonate teemo shrooms with gragas barrels.

Gangplank's Q used to have some weird hidden coefficient that made it break at late games. 1000+ crits etc. on a not-glass-cannon GP were common. I forget exactly what they said it was when they fixed it, but I wanna say it was some huge AP ratio.

Edit: Oh and GP had innate crit chance

Kayle's shield was once a 15 secs or so E skill.