Tried to use Concentration spells but the foes alway go for my casters so ther is no concentration anymore. So dealing damage quick work better for me on tactitian mode.
Do not play D&D 5 tabletop but i am sure that this is not the intension of the rule set.
That's what a Warcaster feat (partially) is for.
Tried it on all difficulties and concentration spells are still useless. Larian was unable to change the AI for the new combat mechanic so they just nerfed concentration spells. As long as all enemies can throw molotowcocktails, jump or fly over the battlefield and have Rambos explosive arrows, concentration spells will be useless. Even if they knock you over you will lose concentration.
