|“||Dude, you may be unbreakable, but we’re not.||”|
|—Meredith to Jeric.|
For this power to be effective, you must be attacked by great power. How strong you are depends on if you will survive or not. For example, Kristen was able to blow up Surgos with one try, but when she attacked Alec with her power, he was only blasted back.
Also, when Callie or Amelia were stabbed, they didn't die immediately because they were more resistant and could hang on longer. Some beings may also only just get knocked out or thrown back, instead of being vanquished.
High Resistance doesn't mean that you can't get killed, though. You can go past someone's resistance by applying a massive amount of power to kill them.
Magical animals like werewolves are highly resistant to some powers when in werewolf form like molecular powers. Alec tried to decelerate Liam's speed when he was a wolf, but it didn't work. Matthew combined his immobilization power with Alec's, but Liam was only stopped for a few seconds.
The Bonum Power is the power of the Bonum Witches combined. It is the most powerful collective power there is, making them the most powerful witches in time. Their bond makes them able to make them resistant to powerful attacks, almost to the point where they are immune. If all six of them were alive and in the coven at once, they would've been immune. This is likely because they have a very powerful form of high resistant. For example. Matthew threw fire at Kristen when the rest of the coven was present. She was only knocked back, but not burned at all.
Beings with telepathy or empathy possess a stronger verson of high resistance compared to other abilities since they can control the powers of others via mind or emotions. This is shown when Matthew was testing Cristina at his dinner party. She only stumbled back or flinched a little when he used his powers on her.