I think this game commits the same significant error most action MMORPG's have committed as of late when it comes to damage delivery by some mobs.
That is, the autoattack damage, with little tell or windup from a mob, does immense amounts of damage relative to a player's health pool.
What this means is that if a person doesn't want to get 2-3 shot randomly, they have to spam block and activate abilities through block, because the attacks are not properly telegraphed.
The Storm Astronach mob is a large culprit here. People will think of his charge up attack, which to be fair is stupidly broken against melee players since block doesn't even work so well against it.
But the real problem with mobs like the astronach and veteran caster mobs who do fast, untelegraphed autoattacks that hit for large amounts makes for poor gameplay.
Tanking in this game or even damage avoidance is not about skillfully dodging abilities or interrupting them. The way it actually works is that if the mob is CC'able, you want to CC it 24/7 to avoid the bucketloads of constant damage it does, and if it can't be CC'd you basically have to hold block and keep it taunted.
Holding block constantly is not an engaging way to combat let alone tank. The damage from autoattacks needs to be vastly reduced, and instead that damage should be moved to telegraphed charged up strikes. So that when you block damage it is skill based instead of keeping up block all the time in hope one of those random quick swings lands while you are blocking.