In early game, especially if there is an enemy Krul , make sure to out level everyone, and don't gank too much. If you are going to gank, wait in the brush and rush at your opponent. In team fights make sure to attack the weakest enemy, such as the sniper. A good combo is run into the brush, wait for Shadows Empower Me to kick in, then use Dead Man's Rush to become invincible, and finally use your Spectral Smite to finish them off when they have low enough health.
Item Explanation
Breaking Point - The reason you should get Breaking Point is because the longer you are in a fight, the stronger you will get. If you have full stacks of breaking point you can basically 1 hit kill heroes. Get this item before anything else, except boots.
Journey Boots - You should almost always get Journey Boots, if you have sufficient gold. The reason for this is because Krul is incredibly useless if he can't keep up with his enemies, so if they can outrun you, you won't be able to do damage.
Tornado Trigger - As you may have guessed, this build focuses a lot on attack speed. This is because high attack speed means that your stacks will add up extremely quickly. Attack speed is also great because if you get enough attack speed you will be able to regenerate incredible amounts of health and your enemies will not be able to do enough damage to kill you. Just like Krul says, "It's like pulling off a bandage, just gotta do it fast."
Aegis - This item is good if you are up against heroes with a lot of blue or ability items, such as Shatterglass or Broken Myth . This is because it is high in shield, which defends from abilities.
Metal Jacket - Metal jacket is the opposite of Aegis because it protects from red or weapon items, such as
Sorrowblade or Serpent Mask . This is because it is high in armor, which defends from basic attacks
Atlas Pauldron - This is a good item to pick up to counter build heroes with high attack speed. Along with having shield and armor, Atlas Pauldron reduces the attack speed of nearby enemy heroes for 5 seconds. This is very effective, but only if the enemies are also building Tornado Trigger .