Tips to Use Tidehunter (Dota2)

• Blink Dagger is a commonly built item on Tidehunter, used in conjunction with Ravage to initiate.

• Anchor Smash is a great way to clear creeps and farm for Tidehunter. Due to its low Mana cost, it can be used to harass enemies, especially melee heroes.

• Do not underestimate the 40% damage reduction from Anchor Smash. If you use it on a hero with a powerful auto-attack, such as Ursa, their damage output will be severely reduced. With 100% uptime from level 2 onwards, you can keep one or more enemies' attack damage crippled indefinitely provided you keep using this skill.

• Resist the urge to take early levels of Kraken Shell for the block during the laning phase. Tidehunter's two other abilities both scale very well with additional ranks, and if you need damage block you can simply buy a Stout Shield and sell it later for minimal (125) gold loss.

• Remember that while Ravage travels quickly, it does take a brief time to extend to its maximum range. Very alert opponents might be able to blink away or activate magic immunity before they are stunned, so be sure to blink in closer to those heroes to reduce their window of escape.

• Extremely quick fingered opponents may also avoid Ravage by blinking very close to Tidehunter, a small area around Tidehunter exists in which Ravage will not affect very close opponents.

• Should the enemy team have a Rubick, it is critically important to cast another one of your spells (generally anchor smash) after casting ravage, as a skill so devastating could easily be the deciding factor in a teamfight should Rubick steal it. 

source:  http://dota2.gamepedia.com/Tidehunter