For this boss you will be fighting Gundyr a second time, however, he is only slightly like you remember. In this fight, there are no holds barred, and he brings it fast and hard. As you near him, he will once again come to life. Keep your shield up and circle to your right dodging and and blocking if necessary. If you get greedy he will punish you, so only attack once after a successful dodge or block unless you want to trade damage. This boss is particularly susceptible to bleed, so in this case that might be perfectly acceptable, as you will need to hit him often and quick to fill his bleed bar and rip a good chunk of his health right off. Be wary when behind him as he will try to kick you in the face after one attack if you are directly behind him. It’s easy to dodge and you can start to predict it by your positioning after a short while. Keep moving your right and keep dodging, only attacking once when you have an opening if you want to play it safe.
In phase 2 he will do an AoE knockback and then charge you with his halberd. Getting caught in this attack will all but kill you. I suggest backing away and dodging to the right at the last second, or you can dodge straight forward into him, as this puts the spin of his halberd behind you, missing you entirely. This phase is extremely difficult as he gives few openings and if you lose patience and try and burn him down by sneaking in attacks when you shouldn’t you can get yourself killed.
Don’t heal unless you are 110% certain you can pull it off, and dodge instead if you don’t think you can. Dodging is the key to this fight. You will need to dodge far more than you attack in this phase, possibly more so than any fight up to this point, and maybe even more so than any fight in the game. Don’t be upset if he still hits you now and again, it’s going to happen, you’re just trying to limit the number of times it happens.
As found on Youtube