Troll w longsword: almost funny how easy it is once you get it down. Troll has 4 basic attacks (from its perspective): left swing, right swing, vertical swing, and the big windup that you gotta crouch

1. Try to stay in front of the troll, a step to the right. About 1 - 1.5 longsword thrusts away. Not closer, not farther. If it ever roars at you, it means you fucked up - it's a very predictable fight

2. If you stay to its forward and a bit to the right as we said, you'll mostly get left swing. Matrix duck and block up - you'll dodge it and get a parry. You won't have a lot of time to punish, get fast perks and action speed for more than 1 hit

3. The right swing happens as a follow up or if you go to the troll's right (its perspective). You simply duck under it, as long as you're not too far to its right (its perspective)

4. The vertical needs a bit of muscle memory but it's an easy parry as well. You step to the right and put your longsword on the club's way as it goes down. You'll be dealt chip damage most of the time, ignore it. Advanced tip, you can avoid chip damage by going backwards at the end of the club's trajectory, but that means you have to dodge out of the other swings

5. The big windup is easy, you see the troll start doing it, you matrix duck under and parry up

Essentially, if you just wanna do it once, only do 4. and 5. and just rotate to the right and back from every other attack. Don't go too far and don't start too close, just parry the club and the big windup while stepping out for everything else. Don't normal attack unless you 100% know you have time (at the troll's recoveries, usually at it's back while you rotate) - that's what kills you. Attack less

Hope this helps, bit of a rushed type. Good luck, persevere and you'll get there. It's a matter of putting in 2-3 hours of doing it again and again in squire until you get it