Cauterize
One of the better red items in the game. This item should be bought if you have a weapon that deals area damage, if the enemy has a support champion like Pip, Grohk or Grover. It's also a great item to bring to the very first fight if you notice the enemy has a lot of green items, namely because they'll be 30% less effective. At level 3 you'll be able to almost completely disable healing for anyone you shoot!