Tips to Use Bloodseeker (Dota2)

• Bloodseeker, whilst being an efficient jungler and dual laner, is also a prime choice for solo mid, as it gives him easy access to the side lanes for ganking.
  • Reaching level six as quickly as possible should be a priority of the player; ganks should not usually be attempted before he has his ultimate.

• Blood Bath gives Bloodseeker significant staying power in lane, healing him whenever he last hits or denies a creep.
  • An early Quelling Blade will help you get the most benefit out of Blood Bath.
  • Thirst is especially useful for allowing for clear targets on a team with no map vision or communication. Otherwise, its best for greatly increasing the risk under which weakened enemies move out or providing conditional speed.

• Leveling Bloodrage causes it to turn into a steroid with a more powerful attack damage buff on every level, but it also serves as a powerful early game nuke and disable. The steroid effect on a fully-leveled Bloodrage is very powerful, often on par with the full arsenal of buffs carried by a given team.
  • Bloodrage should be cast on enemies beginning an engagement to prevent nukes. If Bloodseeker is laning against supports it is an extremely useful spell. Late game, it becomes a dedicated steroid for Bloodseeker or other carries or to twitch disable big caster threats such as Enigma or Earthshaker.
  • At level 3 it can be used almost continuously, since it has a short casting animation.

• Rupture is one of the best skills to intercept an enemy hero that is chasing your allies, especially since it goes through magic immunity and does full damage regardless of armor and magic resistance. Heroes with high mobility like Anti-Mage, Lycan, Queen of Pain or Night Stalker suffer devastating damage when Ruptured as they are chasing or running away.

• When ganking it is sometimes best to save your Rupture for when your target begins running away rather than right at the beginning of the gank. You may want to follow up on an allied disable using Bloodrage to silence the target and saving Rupture should the target not die during the initial damage done.

• Bloodseeker is the fastest hero in the game when Thirst is level 4 with 5 heroes below 50% of their max hp.

• Each individual Meepo will add to the Thirst bonus stack.

• Maximum speed with Thirst is 1852. To reach it, you need Eul's Scepter of Divinity, Sange and Yasha, Boots of Travel, Phase Boots, Mask of Madness, Shadow Blade (on Bloodseeker, activate items in order MoM-Shadow Blade-Phase Boots), Kobold Foreman's Speed Aura, Spirit Breaker's Empowering Haste Aura, Io's Tether, Sven's Warcry, Ogre Magi's Bloodlust, Necronomicon Archer's Attack Speed and Movement Aura and activated Drum of Endurance. 

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