Almost all attacks in Sekiro: Shadows Die Twice can be blocked or deflected, the only ones you really need to watch out for are the special attacks preceded by a red kanji icon.
Special attacks with red kanji icons come in three flavours: thrusting, sweeping, and grabs. Thankfully, all three can be avoided or countered.
Thrusting special attacks can be easily countered with the Mikiri Counter if you’ve unlocked it, opening up the enemy for an attack of your own. Look for the enemy moving their arm back when the red kanji appears, and then press the Circle button (B on Xbox One) without touching the analogue stick to perform a Mikiri Counter. If you haven’t got the Mikiri Counter, simply dodge left or right to avoid a thrusting attack.
Sekiro‘s sweeping special attacks, on the other hand, can be bested by jumping at your opponent and then jumping again when you’re close to them to deliver a kick. You can then get a hit or two in before they regain their balance. Sweeping attacks are a little bit trickier to spot than thrusting attacks though.
Lastly, when an opponent readies up to perform a grab special attack in Sekiro, your only choice is to dodge it. Most grabs can be avoided by dashing backwards to create some room between you and your opponent. Some enemies, like the Chained Ogre for example, have grabs with obscenely long range though. For those grabs you’re better off dodging to the left or right, but don’t dodge too early as the grab is likely to home in on you a little.
Master the art of dodging or countering Sekiro‘s special attacks and you’ll have a much easier time dealing with the enemies thrown at you. Good luck!