Larian Studios Forums Baldur's Gate III Baldur's Gate III - Suggestions & Feedback offhand attack notice

In D&D rules, you cannot use bonus action for offhand attack, unless you already made melee attack with main hand this turn (either with action, or haste's extra action).
In short you can't cast spell and do offhand attack (with exception on when spell actually perform melee attack as part of spell).

Not true, a Valor Bard at level 14 with battle magic can. Technically, it's just an attack after casting a spell as a bonus action, not an off hand attack, but in practice the results are the same. But Larian doesn't seem too concerned with balance between classes, and some classes having special skills. It could be a bug, but honestly, I suspect it's like many of their other changes they've made to 5e, and done to warp 5e to their interpretation. Balance be damned.