Same thing they showed for the Kethric trailer; some clips of gameplay with cool moments and thematically appropriate voice over. Only this time about multiclassing.
D&D isn't designed to be perfectly balanced, Wizards have stated in the past that there will always be overpowered combo's and spells and they like it that way. So don't expect a fully fleshed out and balanced game, as it isn't meant to be. It's meant to be fun.
This is all true, but Larian has made a bunch of changes to how the system works, so there's no telling how things are going to react specifically because there's so many combinations and thus lots of potential for things to go wrong.
