Harassment enemies limits their XP/CXP gain, allowing the harasser to gain an upper hand in mid- to late game.
Harassment can be done in many ways:
- Prevent your opponents from scoring minion kills by blocking their attacks (best done with steel and other tank heroes).
- Attacking enemy heroes directly and forcing them to pull back.
- Continuous use of CC effects to stun, root, or push them away.
- Attacking enemy heroes with high damage abilities.
Tanks and other high durability heroes may not be much affected by attacks, especially mid-game.
Harassment is primarily useful early game, but overuse can limit heroes' growth if used too much.