Monsters with multiple melee reach get Attack of Opportunity from furthest?

Monsters w/ multiple melee reach get AoO from furthest? Ogre’s large & has only 5′ melee reach; AoO @ 5′ reach?

Wizards have insane damage (Meteor Swarm). Will other classes, like Fighters, be able to keep up?

The overchannel ability for wizards. Can it be used to max cantrip damage?