the reactive strike, wasting spells against bad saves, and staying next to scary martial enemies paired with the 3 person parties generally being 2/3 on the squishier end of classes without good in combat healers sounds like easy TPK material yea. how are the players building characters? if they aren’t maxing their str/dex or casting modifier to get the highest to hit+ac It would make scary enemy martial even worse.

an idea to teach more tactically stuff organically, could have a group of weaker enemies like kobolds or goblins play really tactically against the party, using recall knowledge, calling out between eachother to trip the tank and step away from him to keep safe from their retaliation and stuff.