Half cut, Death March, defeated Olgierd Von Everec without getting hit a single time (minus the 11 or 12 times he slammed into my Queen shield which exploded in his face).
Funny thing too, during the fight, he charged and knocked one of his own men into the fire; the guy caught fire and burned to death. Hadn't seen that before.
Hearts of Stone is such a great expansion. In my opinion, a clear step up from the main story - which was already fantastic. The main story is really more like a series of novellas with an overarching epic plot line: it splits neatly into four parts - the first starting with White Orchard and Vizima and set mainly in Velen, the second set in Novigrad and the surrounding regions, the third set in Skeligge, and the fourth starts in Kaer Morhen and Isle of Mists before moving to Novigrad, Tir Ni Lia (or whatever) and finally to Skellige finishing the first arc (The Wild Hunt).
Then Hearts of Stone is part 5, but a separate, independent story and its own arc - the shortest but high quality. The third arc, and the sixth book, this time a novel, is Blood and Wine. If I haven't said it already, Blood and Wine is like the dessert meal of the game - it's like a fairy tale taking place in the most beautiful location in the game - and while Beauclair is technically a smaller city than Novigrad, it's almost as large and feels larger, because much more of the city is useful and there's a lot more individuality about the parts of it. The story revolves around the wine industry, manorial/feudal society, high medieval period fairy tales, and vampires (good ones, the neutral, and the evil). Also, the area has a different tone from the rest of the game, more cultured, wealthier, and for once the world doesn't feel like a bunch of suffering under the clash of a violent and murderously oppressive Empire against an even more evil and oppressive empire that is putting minorities into death camps - it's basically Soviets vs Nazis and the world is everyone else stuck between. Toussaint, where Beauclair is located and the story of Blood and Wine takes place, is far more pleasant of a story - but I don't know if it would taste as sweet if it didn't come after the rest of the game.
But anyway, for now it's Hearts of Stone. I love this story, it's brilliant... a bit depressing at times (Iris), and joyous at others (Shani/Wedding).
And yeah, while I did defeat Olgierd in one go - it took me about 15-20 to beat that damned frog! One-hit kills are not fun. The trick is dodge-dodge-dodge-dodge and every now and then you have a short 2-3 second window to land a big hit. Do that over and over again (Oriole potions to absorb poison), and eventually you'll win. It was not a fun fight after the first 2 or 3 goes, and downright miserable by the later fights, the last few I kept getting him down to about 10-25% and then BAM! Tongue-shot and dead.
The Ofieri Mage afterward, which I recall was very difficult the first time I played this game, was (even on Death March) a trivial battle compared to the frog.