throw your arrows away since they deal like 0 damage to yagluth, grab a frostner, bonemass buff and fire resist, bring a couple hp potions/stamina potions and as long as you don't get glitched inside his hitbox while meleeing him you should be able to tank almost all of his damage (while backing up to heal while getting low every once in a while). There's really no optimal way to dodge his attacks while dealing enough damage, you just gotta tank it.